96 MAZATIiAN BIVALVES 



A piizzKng little shell, of whieli were found only one minute 

 valve and a larger fragment. Eemarkable for the very stout 

 ribs, \vell armed with coarse tubercles, and for the Lucma-like 

 shape of the dorsal margm. 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. 'M, 

 lat. -04, alf. -03. 

 Sa6.— Mazatlan; extremely rare; in shell washings ; L'pool 



Col. 



Tablet 463 contains the valve. 



Family LUCINID^. 

 Genus LUC IN A, Bmg. 



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 fi-om 

 the West coast of S. America. Peeve describees 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 

 Acapulco. 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 LucinjE are not 

 at aU 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. occidentaUs, JRve. 

 (olini 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 Modiolae. 



136. LuciNA (Codakia) tigeeina, Lin. 



Venus tigerina, Linn. Si/st. Nat. p. 1133-4.— i?o;-« 3rus. p. 70.— 

 C/iemn. vii. p. 6, t. 37, f. S90-l.—Schroeter Einl. iii. p. 136.— 

 Mont. Test. Br. p. 119, t. 4, f. I.— Dorset Cat. p. 35, t. 1. 

 f. U.—DilUo. Cat. vol. i. p. 191. no. 76 :— ^'c. 



Cytherea tigerina, Lam. An. s. Vert. ed. 2, vol. 6, p. 318.— 

 Turt. Dyth. Br. p. 161, pi. 10, f. \2.—Flem. Br. An. p. 445. 



