96 MAZATLAN BIVALVES 
A puzzling little shell, of which were found only one minute 
valve and a larger fragment. Remarkable for the very stout 
ribs, well armed with coarse tubercles, and for the Lucina-like 
shape of the dorsal margin. It has about 10 ventral ribs, but 
the species probably has more when adult. If then of the 
same shape, it may take the name of C. lucinoides. Long. ‘04, 
lat. ‘04, alt. °03. 
Hab.—Mazatlan; extremely rare; in shell washings; L’pool 
Col. 
Tablet 463 contains the valve. 
Famity LUCINIDA. ~ 
Genus LUCINA, Brug. 
This genus, so abundant in the Atlantic, and especially in 
the West Indies, appears very rare on the Pacific coast of 
America. C.B. Adams records only one species from Panama, 
and this does not belong to the genus; D’Orbigny none from 
the West coast of S. America. Reeve describes 3 species 
(fibula, eburnea, and calculus) discovered by Mr. Cuming, be- 
sides L. punctata and muricata, previously known; and L. 
annulata from ? California. Dr. Gould has another, from 
Acapuleo. Only one small species was at all common in the 
Mazatlan collection ; though there is evidence of the existence 
of a tolerable number of others. Some of the Lucine are not 
at all constant in their characters ; the same species sometimes 
displaying, or not, radiating and concentric ribs, and having 
its margins smooth or crenated. Not a few of the species 
appear to have a very wide distribution; L. occidentalis, Rve. 
(olim pecten) being quoted from the West Indies and Ld. 
Hood’s Island, and L. borealis from the British Seas and the 
Philippines. Many of the Mazatlan species were found en- 
tangled in the byssal mass of the large Modiole. 
136. Lucina (CopAKIA) TIGERINA, Lin. 
Venus tigerina, Zinn. Syst. Nat. p. 1133-4.—Born Mus. p.70.— 
Chemn. vii. p. 6, t. 37, £. 390-1.—Schroeter Hinl. iii. p. 136.— 
Mont. Test: Br. p. 119, t. 4, £.1—Dorset Cat. p. 35, t. 1. 
f. 14.—Dillw. Cat. vol. i. p. 191, no. 76 :—&e. 
Cytherea tigerina, Lam. An. s. Vert. ed. 2, vol. 6, p. 318.— 
Turt. Dyth. Br. p. 164, pl. 10, f.12.—Flem. Br. An. p. 445. 
