122 LAND AND FRESH WATER MOLLUSKS 



Valvata sincera Say. 



Valvata sincera Say, Rep. Long's Exp., ll, p. 264, pi. xv, fig. 11, 1824. 



Range. — Northwest Territory (Bigs by, _/?</« Say) southeast Kee- 

 vvatin in Attawapiskat and Kawinogans Rivers (Mclnnes) and the 

 southwest point of Anticosti (McCann). 



This shell, according to Say's original description and figure, is " sub- 

 globose-conic " with "nearly four whorls," "finely and regularly 

 wrinkled across," with a large umbilicus "exhibiting the volutions,' 

 and a diameter, at right angles to the axis, of slightly less than three 

 millimeters, as engraved on the plate in Long's Expedition. I have 

 not seen any shell corresponding to these characters from the northern 

 United States, but Dr. Whiteaves has kindly sent me for examination 

 some shells from southern Keewatin and Anticosti which may prove 

 to be Say's sincera. In the literature and in collections we find the 

 e^C'ax'va^\.& tricar inata (^simplex Gould) and all the non-carinated forms 

 of the United States generally labelled ' sincera Say,' ' simplex Gould,' 

 etc. Those specimens of tricarinata which preserve the ' subglobose ' 

 outline have an umbilicus smaller than the carinate shells instead of 

 larger. The very flat and widely umbilicate form wliich is most gen- 

 erally labelled sincera, following Haldeman's figures, is much more 

 like the cristata of Europe than it is like Say's shell. The specimens 

 which have been called sincera in the literature of the region we are 

 now interested in are, so far as I have been able to examine them, all 

 of the next species. 



The only shells in the National Museum which at all resemble Say's 

 sincera are a series received from Aroostook County, Maine, collected 

 by O. Nylander, which differ sufficiently to be called at least a very 

 marked variety. 



Valvata (sincera var. Y) nylanderi nov. 



Shell small, subglobose-conic, with four whorls of a pale greenish 

 straw color ; surface polished, with faint spiral stria, sculptured 

 axially with thin, sharp, elevated, rather distant lamellae like those on 

 Zoogenites harpa or Planogyra asterisctis Morse ; these lamellje are 

 closer and less elevated on the apical part of the shell ; vertex, includ- 

 ing most of the first two whorls, somewhat flattish or pliaiorboid, 

 after which the shell becomes subconic ; the sutures deep ; the base 

 rounded, with a narrow but very deep umbilicus ; plane of the aper- 

 ture nearly vertical, the aperture orbicular, with simple sharp edges ; 

 the operculum multispiral, of the same color as the shell. Axial height 

 3.2 and 3.4; diameter 3.5 and 3.7; diameter of umbilicus .05 and 



