VALVATA. 



15 



Clear Lake, California. Wm, M. Gabb. My cabinet, and cabinet of 

 Mr. Gabb. A number of specimens of this species are before me, most of 

 them being about two-thirds grown. It has no American' analogue. ( Tryon.) 



Valvata virens, Tkyon, Proc. Phila. Acad. Nat. Sci. May, 1863, 148, pi. i, 

 fig. 11. 



I have added to the fac-similes of Mr. Tryon's figures (Fig. 20) 

 an enlarged view of the shell and oper- 

 culum of this species in Fig. 21.^ The 

 peculiar greenish color of the shell 

 distinguishes it from the other American 

 species. The description may be com- 

 pared with that of V. humeralis, given 



above. Valoata virens, greatly enlarged. 



Fig. 21. 



Spurious Species. 



Valvata arenifera, Lea, Tr. Am. Phil. Soc. IV, 104, pi. xv, f. 36 ; Obs. I, 

 p. 114. On p. 27 of Vol. V it is said to be the larva case of Phrygania. 

 Vide the interesting remarks by Von Siebold on this and similar 

 sacs of Phryganidous and other insects in a paper "On a true Par- 

 thenogenesis in Moths, &c.," translated by Dallas, London, 1857, 

 p. 28, note. See also Conrad, N. Fr. Water Sh. p. 2. 



Valvata cinerea, Say, from Western States, is mentioned by name only 

 by Wheatley in his Cat. of Shells of U. S., p. 29 ; also— 



Valvata buccata, Lea, Schuylkill. 



Valvata lustrica, Menke, Syn. Meth. Moll. (Zeit. f. M. II, 130.) 



Fossil Species. 



Valvata parvula, Mk. and Hdn., Phil. Pr. 1856, 123. 

 Valvata scabrida, Mk. and Hon., Phil. Pr. 1860, 418. 

 Valvata subumbilicata, Mk. and Hon. Phil. Pr. 1860, 430. 

 Planorbis subumbilicatus, Mk. and Hdx. (1856, 120). 



' Eastern North American ? 



2 The specimen figured was received from Mr. Tryon. 



