82 THE NAUTILUS. 



While studying the book I made some notes on minor items, and 

 a few of them may be mentioned here. 



A somewhat strange incongruity is shown in the synoptic tables 

 at the head of each class, that of the Isopleura is carried down to 

 families, those of Gastropoda and Lamellibranchia to sub-orders (the 

 tribes of the former are omitted), that of Cephalopoda to tribes. In 

 a general way, the grouping is carried down to genera, giving shorter 

 or longer diagnoses of the latter where it seemed desirable. 



Pp. 7 and 89-91. Radula. It should have been stated that the 

 radula with its teeth is constantly formed anew, and advancing ; 

 while the teeth at the anterior end are becoming blunt and useless, 

 and dropping off, new teeth at the posterior end are formed. The 

 whole radula is renewed several and probably many times during 

 the life of a snail. Also it should have been said that at least in 

 some Gastropods and probably in many of them, the first teeth on 

 the radula of the embryo are of a shape entirely different from those 

 of the post-embryonal animal. 



P. 18. " The otocysts . . . contain auditory granules or otoli- 

 thes." But in closing the paragraph, the author says : " through 

 them the creeping molluscs preserve their orientation and swimming 

 molluscs their equilibrium." I would emphatically endorse the latter 

 view, as against the otocysts being auditory organs, their structure as 

 well as location, in most mollusca, seems to point in that direction. 



P. 186. Physidse ..." with a narrow aperture." How does that 

 agree with forms like our Ph. ancillaria, etc. ? Nothing is said 

 about the radula so very different from those of other Basommato- 

 phora. 



P. 186. Zonites evidently comprises 1 Zonites s. str., Zonitoides-\- 

 Gastrodonta, Hycdina, etc., (conf. p. 129, 1. 4, Zon. cellarius) ; no 

 mention is made of the differences of the genitalia, the foot, the 

 radula, etc. 



P. 187. Helix also is understood in the ancient, Pfeifferian sense, 

 with " more than 4,000 species, a large number of sub-genera have 

 been established," and some of them are cited. Macroon with its 

 immense (probably meroblastic) ova might have been mentioned. 



P. 188. Pupa, '* shell cylindrical, dextral with obtuse summit 

 . . . ." This will fit most of the Pupilla, Orcula. etc. ; but how 

 about most of the Torquilla, Bifidaria, Pupoides, etc., which are 

 evidently included ? 



1 According to English-French conchological — not political — coalition. 



