15 



At first sight this species would be referred either to P. ru- 

 picola or P. procera. But a closer examination shows that 

 while it has the pale brown lip of the latter, it is a shorter and 

 much more ventricose shell ; and while the number and ar- 

 rangement of the teeth are as in rupicola, the latter has a 

 much more slender form, the aperture is more oblique and less 

 elongated, the apex is obtuse, and the lip is white. 



Notwithstanding the distinctions mentioned above, perhaps 

 most observers, on ordinary inspection, would maintain that 

 these three were merely local varieties of the same species. I 

 will add, therefore, that by means of an excellent microscope, 

 to which a camera lucida is attached, I have made accurate 

 figures three inches in length, which render the differences in 

 form unequivocal. 



Found at Santa Cruz by Dr. R. E. Griffiths, and near Ma- 

 tanzas by John Bartlett, Esq. 



I have inserted this species here, although it cannot strictly 

 be considered as belonging to the United States, because of 

 its proximity to the States, and more especially because it 

 helps to illustrate two of our species. 



PUPA PALLAX. 

 Plate XVI. fig. 16. 



P. turrita, glabra, pallide Castanet, umbilicata ; anfractibus sex convexis ; apertura 

 obliqua, subrotundata^ edentula ; labro albo, valde reflexo, striato. 



" Cyclostoma marginata. Shell turreted, pale horn color 

 or dusky, obsoletely wrinkled across ; suture rather deeply 

 impressed ; volutions six ; aperture suboval, truncate trans- 

 versely above by the penultimate whorl, nearly one third the 

 length of the shell ; labium nearly transverse, color of the ex- 

 terior part of the shell ; labrum equally and widely reflected, 

 thick, white ; umbilicus distinct. Length | inch." (SAY, 

 Journ. Acad. Nat. Sc. II. 172.) 



This shell is clearly not a Cyclostoma, and on that account, 

 as Mr. Say suggests, the specific name must be changed. As 

 the shell afterwards described by him under the name of Pupa 

 fallax (Journ. Acad. Nat. Sc. V. 121.) is only a finely devel- 



