FAMILY TURBINID^ — VALVATA. 119 



the passage to sincera. Some eminent conchologists suppose this, and perhaps the following, 

 to be but mere varieties of tricarinata. It approaches the V. liumeralis of Say, from 

 Mexico ; but it is smaller, not so much depressed, and has a wider umbilicus. 



Valvata sincera. 



PLATE VI. FIG. 127. A. B. — PLATE VI. FIG. 128. Monstrous variety. 



(STATE COLLECTION.) 



Valvata sincera, Sav, Long's Exped. St. Peters. Vol. 2, p. 2G1, pi. 15, fig. 11. 

 F. id, Adams, American Journ. Sciences, Vol. 40, p. 2G7, 



Description. Shell small, subglobose, conic. Whorls nearly four, accurately rounded, 

 finely and regularly wrinkled across. Aperture not interrupted by the penultimate whorl, nor 

 appressed to it, but merely in contact ; the lip not diminished in thickness at the point of 

 contact. Umbilicus large, exhibiting all the volutions. 



Color. Light, often whitish ; the apex frequently purplish. 



Height, O'l. Diameter, 0-2 nearly. 



Var. A. The transverse wrinkles obsolete. 



I have received specimens from various parts of the Slate, and am chiefly indebted to Drs. 

 Boyd and Emmons, and to Dr. Jay, for specimens. They are abundant in Lakes Champlain, 

 Chautauque, Oneida, &c. I have seen a monstrous variety of this species from the collec- 

 tion of Dr. Newcomb (fig. 128), which presents the following characters : 



Shell oblong, subcylindrical. Whorls three or four, rounded, smooth : apex depressed ; 

 first whorl horizontal, tlie following whorls entirely detached ; aperture oblique, oval, slightly 

 angular, and effuse at its point of contact with the body-whorl. Umbilicus small, partially 

 covered by the effuse lip. Color, light waxen. Height, 0' 13; diameter, 1'95. 



In this great deviation from the normal form, it is not unlike the monstrous variety of Helix, 

 described and figured by Ferussac {Hist. Moll. terr. etc. pi. 36, fig. 12). In the cabinet of 

 Dr. Jay, there is a monstrous variety of Carocolla alholahris, in which the wliorls are sepa- 

 rated and the lip efi'use. The specimen under consideration comes from the Mohawk river. 



There is frequently found associated with this and the preceding species, an agglutinated 

 arenaceous mass, resembling them very much in form. This has been described as V. are- 

 nifera, in the Transactions of the American Fliilosophical Society (Vol. 4, p. 104, pi. 15, 

 fig. 36. A. B.), and has since been erected by Mr. Swainson into tlie new genus Thelido?nus 

 (See Lardner's Cabinet Cyclopedia, No. 123, pp. 226, 353). It is believed to be the case 

 of the larva of some aquatic insect, possibly a Phryanea. 



(EXTRALIMITAL.) 



V. pv/poidea. (Gould, Invert. Mass. p. 226, fig. 155.) Shell minute, elevated; whorls four or five, 

 the last nearly disjoined ; apex obtuse. Color, chesHut. Length, O-l. Var. of the preceding? 

 Massachusetts. 



