Febeuaet 8, 1907] 



SCIENCE 



225 



it covers, and as to the way in whicli it covers 

 it. 



It may be doubted whether the review in 

 question performs this function. It leaves 

 the impression that the book reviewed is, on 

 the whole, a pretty poor sort of book, when it 

 is reaUy an excellent one. It is not beyond 

 criticism — no book is. The reviewer indicates 

 some of the weak points, and seems to regard 

 -as weaknesses several of the strong features. 

 A number of the criticisms might be appro- 

 priate if the book were intended primarily as 

 a reference work, but they hardly seem ap- 

 plicable to a book which is intended as a text- 

 book for beginners. An excellent text-book is 

 not necessarily the best book for reference. 

 The classification of subject matter for ideal 

 books of the two types would be, in many re- 

 spects, very different. In a text-book, it is 

 certainly no weakness that one must ' go to 

 three or four separate parts of the book ' ' to 

 learn about sandstones,' though this might be 

 a weakness in a book of reference. The re- 

 viewer's attitude leads one to suspect that he 

 uses books for reference only, not as texts, and 

 that this has influenced his point of view. 



In spite of the reviewer's statement, the 

 diagrams of the book are, on the whole, excel- 

 lent and readily understood, and the notes and 

 questions which accompany them are to be 

 especially commended. 



The criticism that the book is largely phys- 

 iographic is nothing against it, and when we 

 remember the class of pupils for whom the 

 book is intended — high-school pupils — the ab- 

 sence of ' references to other books ' is cer- 

 tainly much less serious than the reviewer 

 seems to think. 



The statement that 'the bog ore, silicious 

 and phosphatic deposits that get a brief men- 

 tion in Le Conte are not here referred to ' 

 leads one to make the further suggestion that 

 a book should be carefully read before detailed 

 criticism of this sort is indulged in, for bog 

 ore is mentioned on page 53 and silicious de- 

 posits on pages 52, 178 and 261. Other similar 

 criticisms of the reviewer might be cited. The 

 omission of such subjects as phosphatic de- 

 posits is to be commended in a book of this 

 type, for it must be remembered that most 



elementary books treat of too many, not too 

 few, topics. In the writer's judgment the book 

 takes rank at once among the best of the ele- 

 mentary text-books on geology. 



H. H. Barrows 

 Univeesitt of Chicago, 

 December 10, 1906 



SPECIAL ARTICLES 



THE SIGNIFICANCE OF THE GRASPING ANTENNiE OP 



HARPACTICOID COPEPODS 



The character of the secondary sexual dif- 

 ferentiation of the first pair of antennae of 

 male free-swimming Copepoda and the asso- 

 ciated manner of copulation divide these 

 eopepods into two weU-marked groups: one 

 group in which only one antenna forms a 

 grasping organ and in which the act of copula- 

 tion is relatively short; and a second group 

 in which both antennae are grasping organs 

 by which the male holds the female for a 

 long time in copula. The duration of this 

 union is shown by two records : one of an ap- 

 parently normal pair of Harpacticas uniremis 

 which remained in copula at least twenty- 

 nine and possibly thirty-eight hours; another 

 of a pair of undetermined genus which re- 

 mained in copula eight days, at the end of 

 which both male and female died. The per- 

 sistence of the male is shown by the fact that 

 he can be torn apart, but still maintains his 

 hold until the paralysis of death frees the 

 female. Claus^ observed that the males of the 

 PeltidisB were found in copula with females 

 one molt from maturity and speculated upon 

 the meaning of the phenomenon without 

 arriving at a satisfactory conclusion. 



During the spring of 1906, a large number 

 of copulating pairs of Earpacticus uniremis 

 and Tachidius littoralis appeared in the tow 

 taken in Narragansett Bay and a number of 

 pairs were separated in watch glasses for ob- 

 servation. We were fortunate in examining 

 a pair of the first species just when the female 

 was beginning to molt. The ecdysis occupied 

 about five minutes and as the slough came 

 away, the male, which had been holding the 

 female by the hinder edge of the carapace, 



^Claus, C, 'Die freilebenden Copepoden,' Leip- 

 zig, 1863, p. 71. 



