xxn SCIENCE PROGRESS. 



attention to the special interest which thus attaches to it, but how does he proceed to satisfy 

 the desire for more detailed information? He gives no figure of the genus, and as to the 

 number of species or as to the habits or habitat of any one of them, although two species are, 

 we believe, common enough in this country, he says not a word. He points out it is true how 

 Scolopendrella differs from Campodea, but in what respects it exhibits "a great resemblance 

 to the Thysanura " he forgets to mention. We are told in one place that it has a pair of legs 

 to each segment of the body, and in another that the smaller segments do not bear legs. The 

 caudal appendages are described as hook-like, but why they should appear so to Mr. Sinclair 

 and not to others we need not stop to inquire. The genital opening of Scolopendrella, he tells 

 us, is on the last segment of the body, though he gives no reason for refusing to accept the 

 statements of Ryder, Grassi, Haase and others, who tell us on the contrary that this opening 

 is on the fourth segment. There is of course no reference to the remarkable coxal spurs and 

 saccules of Scolopendrella ; such matters being perhaps considered outside the interest of the 

 .general reader. As the volume is mainly entomological and intended as well for serious stu- 

 dents, a fuller treatment of these structures would not we think be altogether out of place. In 

 other parts of the chapter we notice a few inaccuracies which might with ordinary care have 

 been avoided. Thus we read on p. 59 that " the generative system of Chilopoda differs chiedy 

 in the opening of the genital apparatus at the end of the body instead of in the third segment ; 

 though this difference only separates the order from the Chilognatha and not from the other 

 •orders". The natural inference from this statement is that in all the other orders the genital 

 opening is at the end of the body, but this is true only of the Schizotarsia. Again on p. 43 it 

 is stated that the genital organs of the Chilognatha open on " one of the anterior rings of the 

 posterior part of the body, usually the seventh ". Bat this palpable slip is corrected in another 

 place. Mr. Sinclair's references to Cuvier on page 77 we must also attribute to carelessness, 

 for he could scarcely be so ill acquainted with the history of his subject as not to know that it 

 was Latreille and not the great anatomist " who united the Myriopods with the Insects, making 

 them the first order and the Thysanura the second," and who was thus the first to "claim a 

 close relationship" between the two groups. 



Dr. Sharp's Chapters on the Insects fill more than 500 of the whole 584 pages in the 

 volume. They cover only a part of his subject, which is to be continued in another volume 

 entirely devoted to the purpose. When we consider the vast extent of entomological literature 

 and the number and variety of workers who have been engaged on this branch of science, it 

 must be admitted that to write such an account of Insects as shall embrace all the most 

 valuable and most generally interesting facts and shall at the same time be free from serious 

 errors is by no means an easy task, and requires the exercise of considerable knowledge and 

 judgment. The success with which Dr. Sharp has so far accomplished this task is not 

 surprising to those who know him, but is not the less a matter for congratulation to himself as 

 well as to his readers. His work is in most respects brought well up to date, and puts the 

 reader in touch with nearly all the latest researches in every branch of Entomology, while for 

 the student who wishes to follow up any particular subject copious references to original 

 memoirs are supplied. Dr. Sharp is generally very guarded, almost too guarded in his state- 

 ments, appearing throughout as the impartial recorder rather than as the exponent of any 

 particular views, and seldom giving expression to his own opinion even on matters on which it 

 might be expected to carry much weight. He refers for example without any comment to the 

 suggestion that the elytra of beetles are homologous with the tegulne and not with the anterior 

 wings of other insects, though we have good reason to know that he himself holds the opposite 

 view. Occasionally, however, he betrays some indication of his leanings. Thus on the subject 

 of insect-vision he seems to hold with those who believe that insects perceive only " the lights, 

 shades, and movements of the external world," and can distinguish neither form nor colour. 

 He does not state this explicitly, but such is the inference we draw from the few remarks he 

 makes on this interesting subject. We notice too that in describing the structure of the com- 

 pound eye he omits all reference to the view long ago expressed by Straus-Durckheim and 

 recently revived by Van Patten, that the crystalline cones are really percipient and not merely 

 dioptric elements of the eye. Dr. Sharp's writing is generally very clear, but there are one or 

 two places in which he leaves us in some doubt as to the drift of his remarks. From what he 

 says on p. 89 he seems to admit the probability that in different insects the head is composed 

 of a different number of primary segments, from three to six or even possibly seven, and that the 

 "thorax" also may in some insects be composed of six and in others of three primary segments. 

 Again in a footnote on p. 91, he speaks of the wings as " appendages " which " differ but little in 

 their nature from legs ". If he really holds the remarkable views which seem to be implied by his 

 words in both these cases, we should like him to have stated them a little more clearly. One 



