THE NAUTILUS. 



at Albany, N. Y. Jay (Catalogue, 4th Ed., 1852, 10267) lists P. 

 bicarinatus var. engonatus from Georgia. Through the courtesy of 

 Mr. L. P. Gratacap, of the American Museum of Natural History, 

 I have been able to examine tliese shells. Of the eight specimens 

 in the set, one is a P. campanulatus Say, nearly but not quite mature ; 

 the remainder do not differ from the usual form of bicarinatus, except 

 that the mature ones have a more or less expanded lip, and might 

 well be referred to the form described by Haldeman as var. angi- 

 stomus. None of them exhibit the peculiar flattening of the body 

 whorl characteristic of engonatus. It seems probable that these 

 specimens were referred to Conrad's species on account of the cam- 

 panulate aperture. 



What the P. lautus of H. Adams really is, is a matter of conjec- 

 ture, which can be only definitely settled by reference to the type, 

 if it is still in existence. In the meantime Tryon's supposition that 

 it was a young specimen of his species seems probable enough to 

 warrant its reference to bicarinatus, and thus eliminate it from the 

 list of unknown American species. 



Conrad's P. antrosus is no doubt a form of Say's species, and is 

 quite probably the carapanulate variety described by Haldeman as 

 var, angistomus, under which it will be further discussed. 



Say does not give the locality of the typical form in connection 

 with his original description, but in describing the next species, P. 

 parvus, mentions that both inhabited the Delaware, so that there is 

 practically no doubt but that the types came from that river. The 

 Delaware River form (pi. I, fig. 3) is the common manifestation of 

 the species as it is usually found throughout the United States, 

 Say's description, though brief, is excellent, and leaves little to be 

 desired. An apparent typographical error occurs in the reprint 

 from the 3d Ed. of Nicholson's Encyc, and probably in the original, 

 as it is followed by Binney in his edition of Say's writings. The 

 description as printed reads: "Shell subcarinate above, and beneath 

 translucent." If the comma was placed after " beneath " instead of 

 after '' above," the sentence would be in better accord with (he facts 

 and in all probability with the intention of the author. 



The name adopted by Say in his new s{)ecies is almost a mis- 

 nomer, as the typical form is really not carinated at all, either above 

 or beneath. In both places it is rather a more or less acute angula- 

 tion, and is never raised into a carina as, for instance, in Valvata 

 tricarinata Say. 



