June 5, 1896,] 



SCIENCE. 



847 



power, and then rely upon the acceptance of 

 the terms with the restricted meanings. 



J. W. Powell. 

 Washington, D. C, May 16, 1896. 



SCIENTIFIC LITERATURE. 

 Text-hook of Comparative Anatomy. By Arnold 

 Lang. Translated by H. M. and M. Ber- 

 nard. Part II. London and New York, 

 Macmillan & Co. 1896. 8°. Pp. xvi+618, 

 with many illustrations. 

 The second part of this well-known text- 

 book has been impatiently awaited by teachers 

 of invertebrate anatomy and those who desired 

 a convenient work of reference summarizing 

 the essential facts of the science. Among the 

 numerous text-books of this sort which have 

 appeared of late years, each of which has had 

 its especial merits, that of Lang has reached an 

 easy preeminence, ou account of the wide eru- 

 dition and judicial temper with which the dif- 

 ferent topics are treated. It is, of necessity, in 

 one sense, a compilation and the chief criti- 

 cism which has been made upon the German 

 edition is that the authorities for the facts used 

 are cited in mass as literature and not in con- 

 nection with the particular data due to each. 

 Prof. Lang explains that considerations of space 

 made this obligatory, though, naturally, the 

 work, as a book of reference, would have 

 gained in value as well as size by specific cita- 

 tions. The translation, on the whole, is easy 

 and idiomatic, only occasional Teutonicisms are 

 noted, thovigli it would seem as if some more 

 apposite term than 'Appendage ' might have 

 been used for the supplementary chapters ou 

 Rhodope and Rhabdopleura. The typography of 

 the English edition is much more tasteful than 

 that of the original ; the illustrations are well 

 printed, and the work will doubtless receive a 

 wide and merited acceptance as a text-book. The 

 present volume includes Mollusca, Ecliinodermata 

 and Enteropneusta, but the special criticism on 

 this occasion will be confined to the mollusks. 



It would be superfluous, perhaps, to criticise 

 in this place the general plan upon which such 

 text-books are constructed, but it cannot be de- 

 nied that the comparison, organ by organ of a 

 multitude of animals, leaves a somewhat in- 

 coherent impression upon the mind. As things 



are constituted, anatomists are rarely systema- 

 tists and the systematic part of any of the 

 manuals leaves much to be desired by the 

 specialist. The ideal comparative anatomy 

 would relegate the specific facts to eminent 

 specialists and the comparisons to a systematic 

 genius as editor, a state of beatitude which we 

 are far from approaching. 



Prof. Lang is not an eminent specialist ^in 

 mollusks, but he has a wide knowledge of the 

 literature, and his remarks on mooted points 

 are generally characterized by good sense and 

 sound judgment. The compendium may be 

 said to be, as a whole, representative of the date 

 of 1889, though, in some instances, the text 

 shows later references. 



In selecting an architypal mollusk with which 

 to compare his actual animals, the author has 

 followed Lankester's hypothesis of 1884. The 

 architype is regarded as an animal somewhat 

 between Fissurella and Chiton., bilaterally sym- 

 metrical with a posterior vent and straight ali- 

 mentary canal. We are of opinion that Prof. 

 Verrill's suggestion that the architypal mol- 

 lusk in the main conformed to the type of the 

 molluscan veliger, with a bent intestine and 

 anterior vent, is much more in harmony with 

 our knowledge of the facts ; but space forbids a 

 discussion of the question here. The classifi- 

 cation of the Pelecypods is adopted from Pel- 

 seneer, whose method has been of late pretty 

 thoroughly tested and found wanting, though 

 at the time this text-book was in the making, it 

 was the newest and presumably the most satis- 

 factory. On the whole, however. Prof. Lang 

 has succeeded in bringing together the data in 

 an excellent manner, and the cordial reception 

 of the German edition is sufficient evidence of 

 the estimation in which his work is held by his 

 scientific colleagues. 



Since this work will undoubtedly take a 

 prominent place among the text-books used by 

 teachers, it will not be regarded as hypercriti- 

 oism to use the remainder of our space in point- 

 ing out such items as, on a general perusal, have 

 appeared contestable, erroneous or obsolete. 

 Any work of this kind necessarily contains a 

 certain percentage of such slips, and their pres- 

 ence cannot justly be regarded as condemning 

 it above its fellows. Their correction, therefore, 



