NOTICES OF BOOKS. xxm 



or two other points in his account of the structure of insects call for some slight notice. 

 " Comparison," he says, " suggests that the hypoglottis of Coleoptera may possibly represent 

 the piece corresponding to the mentum of Orthopterists, the so-called mentum of beetles being 

 in that case the sub-mentum of Orthopterists ". This suggestion agrees very well with the 

 statements appearing in so many text-books of comparative anatomy, in which the sub-mentum 

 of Orthoptera is treated as part of the lower lip, and it seems to be supported by the figure 

 which Dr. Sharp gives of the mouth parts of Locusta. But this figure is we fancy not 

 altogether accurate. Comparison really seems to show that entomologists generally are right 

 in regarding the sub-mentum of Orthoptera as part of the head, and homologous with the 

 sub-mentum of beetles. This at least is the view which Waterhouse has taken • after 

 instituting a series of very careful comparisons. Entomologists, however, are not always con- 

 sistent in their use of anatomical terms, and we fancy we see an illustration of the fact in Dr. 

 Sharp's use of the term clypeus. For what he figures and describes as the clypeus in the case of 

 the cricket's head, does not seem to correspond with that part of the head of the cockroach which 

 he denotes by the same name. This is, however, a minor point, and in a writer of less general 

 accuracy than Dr. Sharp would probably escape notice altogether. There are a few omissions 

 which had they been supplied would have added to the value of some of the chapters. In his 

 general account of the embryonic development of insects, he says nothing about the post-oral 

 origin of the antennae or of the appearance of leg-rudiments on the abdomen. His account of 

 the Thysanura, remarkably full in other respects, is deficient in information about the interest- 

 ing character of the mouth-parts, which is all the more to be regretted as it has so much bearing 

 on the suggestion, to which in another place he refers, that the hypopharynx or rather the lobes 

 at its base represent an additional pair of mouth-appendages. The least satisfactory part of 

 Dr. Sharp's work is perhaps that in which he deals with the general classification of insects. 

 Here he discusses the different systems proposed, and shows what every one is ready to admit 

 that none of them is perfect, while at the same time he endeavours to excuse himself for revert- 

 ing to one of the oldest and least natural of all. With his treatment of the different orders, 

 which in this volume include the Aptera, Orthoptera, Neuroptera and a portion of the Hymenop- 

 tera we have no fault to find. Hi really seems to discount his own views on classification by 

 the care with which he points out the close affinities between many of the groups of Pseudo- 

 neuroptera and the true Orthoptera. The work is excellently illustrated, and besides being full 

 of interest for the general reader will prove extremely useful to the student. It promises to be 

 when completed the best modern text-book of Entomology in the English language. 



Grundzuge der Marinen Ticrgeographie ; Anleitung zur Untersuchung der geograpkischen 

 Verbreitung Mariner Tiere, mlt besonderer Beriicksicktigung der Dekapodenkrebse. 

 Von Dr. Arnold E. Ortmann in Princeton, N.J., U.S.A. Mit i Karte. Jena, 1896. 

 96 pp. 



Dr. Arnold Ortmann's clever essay is principally concerned with the distribution of marine 

 animals, objects with which his own studies have made him especially familiar. But he here 

 only uses them to illustrate the general principles which he desires to commend to the student 

 of distribution. 



In a useful historical summary he sets forth the successive attempts that have been made 

 to explain or to describe the real or supposed distribution of animals now living on the globe. 

 At the outset it was not unnatural to fancy that the range of animal groups would bs deter- 

 mined by the zones of temperature. A striking personality like the polar bear for instance is 

 not met with in the tropics, nor are there any arctic or antarctic monkeys, and in the ocean 

 reef-corals will not support a temperature below 66° F. For the division of the zones into 

 regions and subregions, various zoologists selected the range of some particular species or 

 group with which they happened themselves to be best acquainted. But the typical species 

 sometimes turns out to represent nothing but itself, and in the mapping out of provinces and 

 districts there is no security that the boundaries will apply to any animals but those on which 

 they were empirically based. To Andrew Murray is awarded the commendation that as early 

 as 1866 he "inquires into causes for the existing condition of things, and finds them in the 

 geological development of the earth, in the changing distribution of land and water, and at the 

 same time lays stress on the importance of barriers and the limits of range ". Thus was he an 

 important forerunner of Wallace, who first effectively established the fundamental principles 

 that the distribution of life is dependent on the geological history of the earth's surface, on 



1 The Labium and Sub-mentum in certain Mandibulate Insects, by C. 0. Waterhouse. 



