THE NAUTILUS. 27 



more finely sculptured than gualtierana, umbilicus wholly closed. It 

 differs from luurenti by the more deeply descending last wliorl and 

 the much less convex base. Alt. 20, diam. 31 mm. If found to 

 be a different race, it may be called ver. granndce (pi. IV, fig. 4). 



Hellcodonta (^Curacolina) lenticula Fer. The examples before me 

 are smaller than the Sicilian specimens. 



BuUminus quadridens Miill. Several dozen specimens were taken. 

 Dr. Pilsbry, to whom I submitted the form, writes, "The BuUminus 

 is B. quadridens Miill., rather a long form of the species, but 

 certainly that." 



LYMNAEA ATJRICULARIA NEAR PHILADELPHIA. 



BY BAYARD LONG. 



The writer's proper field of activity belongs in the realm of botan) ; 

 tut like many another, he sometimes wanders from the beaten patii 

 of his own special science. A note, however, upon the occurrence 

 of a foreign species markedly thriving in our own natural habitats, 

 and there associating with indigenous forms in so perfectly a 

 naturalized state that only a knowledge of the normal distribution of 

 the species makes it possible to detect the status of its occurrence : 

 such a note seems rather familiar ground, since there is such a host 

 of introduced plants whose migrations must be kept under ol)serva- 

 tion. So the writer may, in a measure, be justified in breaking into 

 Conchology. Botanists make rather a point of putting upon record 

 the early occurrences of foreign elements entering into our flora, 

 because, besides being of an historical interest, a lack of such 

 data, among plants at least, has often led to considerable confusion 

 and error as to what are actually indigenous plants of any given 

 area. Such a condition is probably not so likely to occur among 

 shells, but still it may be of no less importance to have definite 

 record of observations of species becoming naturalized, in case the 

 forms should possibly become widespread and a knowledge of their 

 original centres of dissemination lost. 



In 1910 there was brought to the Philadelphia Academy by 

 Samuel R. Jacob some shells which he had casually collected in 

 Europe, and also some specimens of Lymnaa auricularia (Linn.) 

 which, however, were said to have been collected from near 



