244 LAKE SUPERIOK. 



2 Physa vinosa, Gould. Northern coast, Michipicotin. 



" ancillaria, Say. Niagara, Sault St. Marie, Michipicotin. 

 Limnea jugularis, Say. Northern Coast. 



" caperata, Say. Niagara, Black River. 



" humilis, Say. Michipicotin, Cape Gourganne. 



3 " catascopiuin, Say. Northern shore, Fort William. 

 " desidiosa, Say. Northern shore. 



4 " lanceata, Gould. Pic, Gourganne. 



2 PHYSA VINOSA, Gould, T. tenui, ovato-globosa, badia, spiraliter minutissime stri- 

 ata, epidermide tenui induta ; spira obtusa, anfr. 4, ultimo permagno ; apertura ovato- 

 lunata, | longitud. testae adequante, hepatica ; columella recta, tenui. Long. |, lat. 

 poll. Proceed. Bost. Soc. Nat. Hist., II., 263, Dec. 1847. 



I quote the above description of a species first brought from Lake Superior by Dr. 

 C. T. Jackson, and hitherto found only in the region of that lake. Prof. A. found it on 

 the north shore, at Michipicotin. It is well characterized by its inflated form, delicate 

 structure, striated surface, its wine-red color externally, and its liver-brown color within. 

 It resembles, somewhat, P. ancillaria, which differs in form by having shouldered 

 whorls, and its greatest diameter behind the middle. Unfortunately, the figure has 

 been drawn from a very small specimen, and does not exhibit the characters of a full- 

 grown specimen. (See pi. 7, figs. 10 and 11.) 



3 LIMNEA CATASCOPIUM. There is no slight difficulty in defining the limits of allied 

 species in this genus. While real specific characters are very few and ill defined, the 

 variations of species are very numerous and wide in their range ; nevertheless, by a 

 certain facies, or by collecting large numbers at a given locality, we are able to pro- 

 nounce shells which are very different in their aspect to be specifically identical. 

 These remarks apply with special force to the species above named. Some of the 

 specimens are elongated and slender, while others are short and ventricose ; some are 

 thin and fragile, others dense and firm ; some are smooth or with a delicately cor- 

 rugated epidermis, others are indented and broken into numerous facets ; some have a 

 very largely developed fold on the pillar, while others present a simple column ; in 

 some the columella is curved and flexuous, in others it is direct ; some have regular 

 and symmetrical outlines made up of cylindrical whorls, while others have a very acute 

 angle and a broad shoulder at the posterior part of the body whorl ; and the color may 

 be amber, brownish, livid or cinereous. There can be little doubt that these wide va- 

 riations have been regarded as different species, as indeed they could not fail to be, 

 were only isolated specimens examined ; but when we come to compare large numbers 

 collected in company, we see the connecting links and the necessity of retaining them 

 under one name. Among them we find L. pinguis, Say, which Mr. Haldeman has al- 

 ready referred to this species ; and also L. emarginata, Say, which, from the few speci- 

 mens he had seen, Mr. Haldeman deemed to be a well marked species. The numerous 

 specimens since brought from the Lake Superior region render it sufficiently certain 

 that it is only a variety of L. castascopium, with the last whorl more or less angular 

 posteriorly, and with a straight pillar which gives to the base of the aperture a pecu- 

 liarly broad and distorted form. 



Amid all the variations, however, there is a certain aspect of the aperture which is 

 characteristic. It is large when compared with that of L. wmbrosa, or L. elodes ; it is near- 

 ly semicircular, while in large specimens of L. desidiosa, where the proportional size of 

 the aperture is more nearly the same, its posterior outline is broad and nearly transverse. 



* LIMNEA LANCEATA, Gould. Testa mediocri, fragili, diaphanii, cornea, attenuata, 

 striis incrementi et striis volventibus argute reticulata ; spiroe anfr. 6 planiusculis, per- 



