54 MAZATLAN BIVALVES 



Genus PClementia, Gray. 

 B. M. Cat. Ven. p. 197. 



82. ? Clementia geacillima, n. s. 



1 C. t. suhtrigona, tenuissimd, alba, diaphana, concentrice 

 liratd, liris rotundis, approximaUs ; postice prolongatd. Intus 

 dent. 3-4 divergentibus, minutis : Ugamento vix monstrante. 



This shell comes nearer to Clementia than to any other 

 genus I know ; nor is there any reason why it should not be 

 found on the American shores of the Pacific. Some may rank 

 it with Tellina. The teeth are more equally divergent than in 

 the typical species. Long. '09, lat. '13, alt. '5. 



Hab. — Mazatlan ; from backs of Chamse and Spondylus La- 

 marckii ; extremely rare ; L'pool Col. 



Tablet 216 contains 1 perfect and 2 broken valves. 



Genus TEIGONA, Megerle. 



Trigona, Megerle. teste Besh. B. M. Cat. Ven. p. ^—Muld- 



feldt, teste Woodw. Man. Moll. pt. 2, p. 305. 

 = Trigonella, Conr. Hinds. 

 = C3i;herea (pars) Lam. 



Known from Cytherea and Dione by the trigonal shape ; 

 niunerous irregular cardinal and long lateral teeth ; and by 

 the velvety periostraca outside the epidermis, of a diill white 

 colour, whicli, being mistaken for dirt, is generally very care- 

 fully cleaned off by collectors. Under the microscope, this 

 appears like an irregular mass of needle-like crystals. 



83. Teigona eadiata, Sow. 



Cytherea radiata, Pt'oi\ Zool. Soc. 1835, p. 23. — Hani. Descr. 



Cat. p. \m.—Soio. Thcs. Conch, p. 619, pi. 128, f. 28—31.— 



C. B. Ad. Pan. Shells, p. 273, no. 446. 

 Trigona radiata, Besh. B. M. Cat. Ven. p. 51, no. 19. 

 Venus Solangensis, B. M. Cat B'Orb. Moll. p. 68, no. 607. 

 Trigona Byronensis, G-rai/, Anal. t. 8. p. 301, 1838. 

 = Cytherea corbicida, Menke (non. Lam.) in Ze'it.f. Mai. 1817, 



p. 189, p. 54 : also Sow. Thes. Conch, p. 614, no. 7 (pars), 



pi. 128, f. 39 (f. 37, 38 excl.) 



