MAZATLAN BIVALVES 69 
97. DionE ? BREVISPINOSA, Sow. 
Cytherea brevispinosa, Sow. Thes. Conch. p. 632, pl. 132, f. 109. 
Dione brevispinata, Desh. in B. M. Cat. Ven. p. 76, no. 70. 
Tablet 314 contains a minute valve which may be the young 
of this species. It has close concentric rounded ribs, and very 
strong teeth for the size. Length ‘03. 
Hab.— Gulf of California, Col. Cuming.—? Mazatlan, jun. 
1 valve; L’pool Col. 
> 
98. Dione crrcinatTa, Born. 
Venus circinata, Born, Test. Mus. p. 61, pl. 4, f. 8.—Chemn. 
Conch. Cab. vi. 312, pl. 30, f. 311.—_Dillw. Rec. Sh. i. 169.— 
B. M. Cat. Sagr. Moll. p. 39, no. 474. 
Cytherea circinata, Sow. Thes. Conch. p. 631, pl. 132, f. 104-6.— 
Horbes & Hanl. Br. Mol. i. 399. 
Dione circinata, Desh. B. M. Cat, Ven. p.77, no. 72. 
Venus Guineensis, Gimel. Syst. Nat. p. 3270, &ce. 
Cytherea Guineensis, Lam. An. s. Vert. ed. Desh. vi. 311, &e. 
Cytherea alternata, Brod. Proc. Zool. Soc. 1835, p. 45. 
Tablet 315 contains a small white valve which may be the 
young of this species: long. ‘08, lat. °095, alé. 05. 
Hab—Cuba, Sagra.—S. Atlantic, Forbes.—Mazatlan, Capt. 
Donnel :—do. Lieut. Green, (Gould ms.) :—do. one valve and 
fragments, jun., L’pool Col.—Var. alternata, Monte Christi, 
in sandy mud, 11 fm., Cuming. . 
99. DionE conctnna, Sow. 
Cytherea concinna, Proc. Zool. Soc. 1835, p. 23.—Sow. Thes. 
Conch. p. 630, pl. 132, f. 99, 100. 
Dione concinna, Desh. B. M. Cat. Ven. p. 74, no. 61. 
Comp. D. affinis, Brod. Proc, Zool. Soc. 1835, p. 45; B. M. 
Cat. Ven. no. 60: and D. tortuosa, Brod. id.; B. M. Cat. 
Ven. no. 62. 
This shell is coloured in sienna brown and white stripes in 
about equal proportions, the brown being darker on the ribs 
and in the lunule. Umbos yellow. Concentric ribs occasionally 
bifurcating. Pallial sinus, long, narrow, ascending. Long. 1°2, 
law lige. le. "75. 
Hab.—Panama, in fine sand, 10 fm. Cwming.—Mazatlan ; 1 sp. 
with D. rosea; LZ’pool Col. 
Tablet 316 contains the specimen. 
