MUSEUM OF COMPARATIVE ZOOLOGY. 177 



goes segmentation, and the germ appears. The rotary motion, which 

 is probably due to ciliary or vital action, consists of two or three turns 

 in one direction and the same number in a reversed one ; and in this 

 reversed vital action during segmentation of the yolk of the egg may 

 lie the secret of sinistral or reversed shells. Several years ago I 

 received from Mr. Garrett a number of species of Partula in alco- 

 hol. These I presented to William G. Binney, Esq., of Burlington, 

 New Jersey, well known to scientists for his work on the anatomy 

 and lingual dentition of Terrestrial Mollusks ; and his observations 

 on Partula are reported in the Proceedings of the Academy of Natu- 

 ral Sciences, Philadelphia, for April, 1873, which may be epitomized in 

 this place as follows : " In the examination of the animals of twenty- 

 three species of Partula he not only found the external characters 

 to agree generically, but the peculiarity of the lingual dentition was 

 constantly exhibited. Nothing remarkable was observed in the ner- 

 vous, respiratory, or alimentary systems." " The jaw differs in the 

 different species in the more or less attenuation of the ends, and also in 

 the number of plates of which it is composed. The lingual membrane 

 is broad, and the denticles vary in size and number in the different spe- 

 cies, as in other Terrestrial Geophila. Excepting that some of the mem- 

 branes had narrower teeth than others, he found no difference in them. 

 The Genitalia differed somewhat in the different species, illustrations of 

 which accompany the paper. Fe>ussac's observations concerning their 

 viviparous character were confirmed, but he had overlooked the fact 

 that the animal possessed the two inferior tentacles." 



Through the kindness of Professor Dall I have received some Partulee 

 in alcohol from the Smithsonian Institution, some of which I have sub- 

 mitted to a microscopical examination of the jaw and lingual dentition. 

 I find the number of plates in the jaw on each side of the median 

 line varies in the same species, as well as in the different species, agree- 

 ing in this respect with other terrestrial Geophila. For example, in 

 P. subangulata Pse. Mss. = P. faba Mart, van, the formula was f g , 

 lt> f#> t§> £$> II- I n P- obesa Pse. Mss. = P. auriculata Brod. var., 

 the formula was §£, |J, §£, §f, §§, §£, Jf. Of P. vexillum Pse., 

 P. Ganymedes Pse., and P. inflata Rve., I possess but one specimen 

 each. In P. vexillum the formula was gg ; in P. Ganymedes, $$ : and 

 in P. inflata, §^. The form of the teeth and dental formula in P. Ganv- 

 medes and P. inflata are similar, the only difference being in the number 

 of rows on each membrane. The shape of all the jaws agreed with the 

 figure of Mr. Binney. Whether the number of plates in the jaw or the 



vol. ix. — no. 5. 12' 



