geographical and geological distribution of animals, scarcely receive more than a passing mention.

The volume before us, which constitutes the second volume of the book, includes those animals which formed the sub-kingdoms, Annulosa and Radiata, in the Cuvierian system; the Vertebrata and Mollusca being postponed until the publication of the first volume. The authors of this present volume, Dr. Gerstaecker and Professor J. V. Carus, divide these animals into five groups, of which the first alone, that of the Arthropoda, has been consigned to the treatment of the former gentleman. This group is divided into the usual four classes, Insecta, Myriapoda, Arachnida, and Crustacea, and the description of the characters of these and of their subordinate groups occupies considerably more than half the volume.

The classification of the Insecta will present some appearance of novelty to the English Entomologist, as it is in accordance with the views generally entertained by the more advanced German school, The Apterous, or so-called Ametabolous orders are got rid of altogether, being amalgamated, as originally proposed by Burmeister, with other recognised groups; the Strepsiptera are referred to the order Neuroptera, and the whole series of insects is thus made to consist of seven orders. But the most striking change to our insular prejudices consists in the peculiar limitation of the first two orders in Dr. Gerstaecker's classification,-the Orthoptera and Neuroptera. The former group includes the whole of the Insecta with an imperfect metamorphosis and biting oral organs; so that besides the ordinary Orthoptera, in Latreille's sense, we have as members of this great order the Termites, Psoci, Perlide, Ephemerida, Dragon-flies, and Physopoda among winged insects, and the Thysanura among the apterous forms. The latter ought certainly to have been accompanied by the Mallophaga, or Mandibulate Lice, but the author has chosen to place them with the true Lice under the Hemipterous order, being induced to take this course by the supposed near alliance existing between the two groups, and because, as he says, by "their reversion to the Orthoptera, they close the circle of the InsectOrders" (p. 287). It seems to us that the latter purpose would have been equally well served by placing these curious parasites in their natural position among the Orthoptera, and their alliance to the Pediculina appears to be one chiefly of general appearance and mode of life.

The order Neuroptera, deprived of all the groups with an imperfect

metamorphosis, appears sadly diminished in importance-it includes only the Planipennia of Latreille, and the Trichoptera of English authors, with the addition, as already stated, of the singular Strepsipterous Bee-parasites. The latter are regarded by Dr. Gerstaecker as most nearly allied to the Phryganida, with which, he says, they agree in the structure of the prothorax, the free, elongated anterior and middle coxæ, the rudimentary oral organs, of which the maxillæ are amalgamated in a similar manner with the labium, and likewise in the radiate venation of the posterior wings," and he cites, as a further proof of this relationship, "the branchiiform respiratory organs detected by Newport on the abdominal segments of the larvae of the Strepsiptera" (p. 79). It does not appear to us, however, that Dr. Gerstaecker has by any means made out his case in favour of the Neuropterous nature of the Strepsiptera,-the characters adduced by him in proof of their relationship to the Trichoptera are for the most part non-essential, and the peculiar organs noticed by Newport, upon which Dr. Gerstaecker lays so much stress, are only supposititiously regarded by him "as imperfect respiratory organs of the nature of branchia." The balance of evidence, especially that derived from the life-history of these curious parasites, seems to preponderate greatly, as shown by Dr. Schaum in a recent paper in Wiegmann's Archiv, in favour of their Coleopterous nature, almost all their most striking peculiarities being paralleled among the Coleoptera by the Meloida.

The division of the Coleoptera into characterisable groups higher than the natural families is certainly one of the greatest difficulties with which Entomologists have to contend, and Dr. Gerstaccker has been unable to get over it. He accordingly adopts the old Latreillian divisions in accordance with the number of joints of the tarsi, although he admits that it is liable to many exceptions in the Pentamerous group, and brings together, under the common term Heteromera, the most "heterogeneous elements." In other respects the author has been most fortunate in his elaboration of the analysis of the Coleoptera, and especially in his selection of characteristic genera, which must have been a work of no small labour in a group so extensive.

Passing over the order Hymenoptera, our author's treatment of which presents no peculiarity calling for special notice, we must object strongly to his primary division of the Lepidoptera into two groups, denominated from the general size of the species in each, Macro- and Micro-lepidoptera. It may be true that certain charac

ters exist of sufficient value to justify the division of the Heterocerous Lepidoptera into two sections, but in any classification professing to show the natural affinities of these Insects, the Butterflies (Rhopalocera) may certainly claim to form a group of higher rank than that of a family. The Diptera also are divided into sections on an unusual principle,-the true Diptera (Diptera genuina, Gerst.), after the deduction of the Pupipara and Aphaniptera, being formed into two groups, according as the pupa is coarctate or not. The group with an obtected pupa includes the Tipuliform and Culiciform families, with the Tabani, Asili, Empida, Bombylii, and some other families, that with a coarctate pupa only the Muscidæ, Syrphide, and Stratiomyide. The propriety of this mode of division seems rather questionable; the pupa in both sections is essentially the same, and the circumstance of its being retained within the dried larva-skin in the one set of forms and not in the other can hardly be regarded as of equal importance with the structural differences by which the Nemocerous and Brachycerous Diptera are distinguished.

Dr. Gerstaecker's seventh and last order of Insects, to which he gives the name of Hemiptera, includes the Rhynchota of Burmeister, with the addition, as stated above, of the Mallophaga. The author refers the Ploteres to the Hydrocores, which is certainly incorrect, but in other respects the classification adopted by him, although not satisfactory, furnishes a good general view of the insects composing this little known order.

The treatment of the small class of Myriapoda presents nothing to call for special notice, but in the classification of the Arachnoidea, Dr. Gerstaecker departs widely from the principles ordinarily adopted in the division of this class into groups. The old sections of Pulmonary and Tracheary Arachnoids are entirely ignored by him, and in place of them he adopts groups founded upon certain peculiarities in the external structure. Thus his first order is denominated Arthrogastra, and includes all the Arachnoidea with "a sessile and distinctly segmented abdomen," whether they respire by means of lungs or by trachea. The groups thus brought together into a single order are very heterogeneous in their character, including, as they do, the Scorpions, Phrynidiæ, Pseudoscorpiones (Chelifer), Phalangidæ, and Solifuge (Solpuga),-nay, Dr. Gerstaecker even interpolates the Chelifers between the true Scorpions and the Phrynidae in his first section of the order which he designates Didactyla, from the presence of didactyle nippers on the first maxillary palpi. We cannot

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but think that Dr. Gerstaecker would have done better had he allowed more weight to those "many essential differences" which he admits to exist between the forms thus grouped together within the limits of a single order, of which the nature of the respiratory organs is the most striking, especially as these differences are reflected, or at least accompanied, by corresponding peculiarities even in the external structure. His order Arthrogastra consists of essentially incongruous elements, and we cannot expect ever to see it generally adopted. Of the remaining orders of Arachnoidea little need be said, the Araneina and Acarina constitute well-marked groups, as to the limits, of which there can be little difference of opinion, and the only change adopted by Dr. Gerstaecker consists in the separation from the latter of the Tardigrada and Linguatulina, of which he makes distinct orders. The Pycnogonidæ are also justly regarded by Dr. Gerstaecker as Arachnoidea,--he places them in a distinct order, to which he gives the name of Pantopoda, in allusion to their being apparently composed only of legs.

In his general arrangement of the Crustacea, Dr. Gerstaecker seems to us to have been particularly successful, and as this class, from the multitude of forms which it includes, and the marvellously varied life-history of its members, is perhaps the most important and interesting to the experienced Naturalist of all the Arthropod classes, and at the same time the most difficult for the student to obtain a clear notion of, we cannot but regard it as a fortunate circumstance that, in this Manual of Zoology, it has been treated in so philosophical a spirit.

The orders of Crustacea recognised by Dr. Gerstaecker are seven in number. In the first and highest of these, under the name of Decapoda, he includes the whole of the Podophthalmous Crustacea, justly considering that the Stomapoda, whilst still constituting a subordinate group, form an essentially uninterrupted series with the other Decapoda, from which they are distinguished by characters of less than ordinal value. Following the example of Kröyer and Spence Bate, Dr. Gerstaecker unites the Whale-lice to the Amphipoda, and thus gets rid of the Latreillian order Læmodipoda,-the family Pranizidæ, including the single genus Anceus (of which the researches of M. Hesse have shown Praniza to be only a larval and female form), is placed in an appendix to the Isopoda, the author remarking justly upon the singular resemblance of these curious Crustacea to the Decapoda, which, with other peculiarities, renders it somewhat difficult to settle accurately their systematic position.

The King-Crabs constitute a fourth order, leading naturally from the Malacostracous to the Entomostracous Crustacea, and for this Dr. Gerstaecker adopts the name of Poecilopoda, applied by Latreille to a heterogeneous assemblage, in which these animals figure together with Argulus, Caligus, Anthosoma, and several other parasitic genera. Why he has rejected Latreille's term Xyphosura for the King-Crabs, or rather sunk it into a family name does not appear; it is certainly the most characteristic name for the order, and the change is by no means an advantageous one.

The fifth order, Branchiopoda, receives from our author a wider extension than is given to it by Milne-Edwards, embracing the Fossil Trilobites and the Cypridiform Crustacea, in addition to the Phyllopoda and Cladocera of Latreille. With regard to the precise sytematic station of the Trilobites (which Dr. Gerstaecker erroneously describes (p. 395) as "the oldest representatives not only of the Anthropoda, but of all animal organisms") we certainly possess no positive evidence, and although Burmeister's investigations have shown that their nearest allies in existing nature are the Phyllopoda, they nevertheless present characters which, taken in conjunction with their limited distribution in time, would seem to justify our regarding them as a distinct order. The difficulty of placing the Trilobites in a definite position is, however, only a negative one, arising from our ignorance of those parts from which the essential characters of the orders are derived, but the Ostracoda have evidently presented our author with a positive difficulty, which has interfered materially with his definition of the order Branchiopoda-a difficulty which he has but imperfectly got over, by assuming that the two pairs of branchiferous footjaws in these Crustacea are in reality to be regarded as belonging to the series of abdominal feet. This is a point which may be cleared up by future researches,—in the meanwhile it is certainly better to place the Ostracoda in the same order with the very analogous Daphnidæ, than to adopt the only other course, that of establishing a distinct order for this small group. This indeed is the only alternative open to us, for Dr. Gerstaecker's sixth order, to which he restricts the term Entomostraca, must be regarded as a perfectly natural group. In it he includes, besides the Copepoda, the whole of the parasitic Entomostraca of authors, forming a group which it is perhaps difficult to characterise satisfactorily, but which, from the close similarity in the young animals, and the agreement in many important points of the life-history of its mem