CALL - ON NEW MOLLUSCA. 5 



This form was dredged by the writer, in August, 1883, in great num- 

 bers in Utah Lake, near Lehi, not far from the head of the River 

 Jordan. It is intermediate between Valvata sincera Say and V. virens 

 Tryon. From the first it differs in the unicarinate upper whorls, in 

 being more elevated, in possessing a very much smaller umbilicus, and 

 in its greater size. From the second it differs in color, size, carination, 

 and form of aperture. It resembles, in some respects, V. unicarinata 

 De Kay (= V. tricar inata Say), but differs in size, ornamentation, and 

 form of aperture. Specimens may be seen in the Smithsonian Institu- 

 tion, in the New York State Museum of Natural History, in the Daven- 

 port Academy of Natural Sciences, and in the private collections of 

 Beecher, Stearns, Dall, Aldrich, and the writer. 



Genus RADIX Montfort (i8ioj. 

 Radix utahensis, sp. nov. 



(Plate I., Fiffs. 7-9.) 



Radix ampla, var. ^tta/lensis, Call. Bull. U. S. Geol. Sur., No. n, p. 47, Plate 

 VI., Figs. 7-9 (1884). 



Shell .globose, somewhat umbilicated, irregularly costate, light horn 

 color, nearly pellucid; spire rather small, conical; whorls four to four 

 and one-half, convex, somewhat flattened above, giving rather a shoul- 

 dered appearance to the whorls, rapidly increasing in size, the last 

 whorl being inflated, with numerous rather marked transverse costse, 

 minutely wrinkled; suture somewhat deep, regularly impressed; aper- 

 ture elongately ovate, effuse, approaching patulous, pearly white within ; 

 outer lip simple, the margin connected by a slight calcareous deposit; 

 columella somewhat twisted, but straight in front. Dentition unpub- 

 lished. Length of largest specimen, i6.82 mrn ; breadth, 8.88 mm . The 

 average of nine specimens gave a length of 13 4o lllm , breadth 7. io mm , 

 with about the same ratio for corresponding measurements of aperture. 



Length, 13. 40'"'"; breadth, 7.io mm . 



Length of aperture, 9.00'"; breadth of aperture, 5.90""". 



Habitat and Station. Lake Utah, Lehi, Utah. 



This is a rare form in Utah Lake, its only locality so far as known. 

 Its nearest affinity is Radix ampla Mighels. In the preceding refer- 

 ence its relation to Polyrhytis kingii Meek has been noted. It was 

 associated with abundant specimens of the Valvata herein described, 

 and with Fluminicola fusca Haldeman and Sphcerium dentatum Halde- 

 man. Specimens may be seen as above. 



