MAZATLAN BIVALVES 77 



ventral margin. The colour is very light brown, more or less 

 spotted or stained with darker in zigzag stripes or blotches. 

 The ligamental area is smooth, and marked off by a decided 

 keel on each side. The keel is almost always painted with spots, 

 even when the rest of the shell is without them. Long. 1*34, 

 lat. 1*58, alt. '8. 



Hob. Real Llejos & St. Elena, in muddy sand at low water, 

 Cuming. Ecuador, St. Elena, D' Orlngny. Mazatlan ; ex- 

 tremely abundant ; L'pool fy Havre Coll. 



Tablet 364 contains 7 specimens with dark patches of brown. 

 365, 7 do. smaller patches. 366, 7 do. very small patches. 

 367, 7 do. dark markings obsolete. 368, 7 do. with generally 

 diffused shade of lighter brown. 369, 7 do. the same broken 

 up into patches. 



110. TAPES GEATA, Say. 



Sow. TJies. Conch, part 13, p. 699, pi. cli., f. 152 : (non Desk, in 



J5. M. Cat. Yen. p. 170.) 

 Venus grata, Say Am. Condi. 1830, pi. 26 (teste Jay, 36 teste 



Sow.) 



Chione grata, Desk, in J9. M. Cat. Ven. p. 140. 

 = (teste Desh.) Venus tricolor, So^v. Proc. Zool. Soc. 1835, 



p. 41. Zool. Beech. Voy. p. 151, pi. 41, f. 7. Hani. Descr. 



Cat. p. 119 .- Wood Swppl. pi. 16, f. 32. (Tapes t.) Sow. Thes. 



Qonch. p. 699, pi. 151, f. 153. 

 = (teste Jay) Venus discors, Sow. Proc. Zool. Soc. 1835, p. 42. 



Hani. Descr. Cat. p. 118 : Wood Suppl. pi. 15, f. 603. M. 



Cat. DOrb. Moll. p. 67, no. 600. C. B. Ad. Pan. Shells, 



p. 269, no. 436. (Tapes d.) Sow. Thes. Conch, p. 698, pi. 151, 



f. 148-150. (Chione d.) Desh. B. M. Cat. Ven. p. 141, no. 65. 

 ? = Venus Entobapta, Jonas Zeit.f. Mai. 1845, p. 66. 

 ?= Venus- neglecta, Phil. Abbild. ii. 62, pi. 4. f. 3, (non Gray.) 



This shell differs from T. histrionica in not having the smooth 

 ligamental area nor the enclosing carinse. The lunule also is 

 less distinct. The large specimen is much more tumid, and 

 more irregularly marked. The hinge teeth are much closer 

 and smaller in proportion, and are very slightly bifid. Pallial 

 sinus less angulated, smaller. Internal crenations less distinct. 

 An intermediate specimen has one tooth in each valve strongly 

 bifid, and is flattened like T. histrionica. The youngest speci- 

 men scarcely displays bifidity, is much more coarsely and 

 regularly marked, and has the pallial sinus rounder. It is 



