152 



MAZATIAN BIVAliVES 



fry. It probably resembles P. costellata, Conr. from the 

 Sandwich Is., but that is described as having both beaks alike. 

 The smallest specimen is '05 in length ; the largest, long, (the 

 diagonal of the lozenge) 1"12, lat. '68, alt. *17. 



Hab. — Mazatlan ; on I. Chemnitzii and Spondylus calcifer, 

 extremely rare : L'pool Col. 



Tablet 689 contains 1 pair and 2 valves, very young. — 690, 

 the most characteristic specimen, in situ. 



Family PECTINID^. 



Gextjs PECTEN, Miill. 



Of this (in most places) abundant genus only 3 very small 

 valves were found. The neighbouring genus Lima was alto- 

 gether absent. 



207. Pecten cieculaeis. Sow. 



Proc. Zool. Sac. 1835, p. 110.— ffanl. Bescr. Cat. p. 271. 



Dull ash, variegated with chocolate ; ears very large ; inter- 

 stices near the umbo finely decussated. The opposite valves 

 differ in sculpture.— io??pr. "28, lat. "26, alt. "12. 

 Sah. — Guaymas ; in sandy mud, 7 fm. ; Col. Cuming. — St. 



Vincent's [?] Hanley. — Mazatlan ; extremelv rare : L'pool 



Col. 



Tablet 691 contains the only valve I found. 



Family SPONDYLIDtE. 

 Genus SPONDYLUS, Linn. 



208. Spondylus calcifee, n. s. 



S. f. maxima, ponderosd, solidci, plerumque orbiculari ; nihro- 

 purpurea ; valvd superiore cos t is mini m is ac ill eat is 

 creherrimis tectd, hue et illuc costis irregularibns squamosis ; 

 squamis curtis, ad basim arcuatis, supra foliatis ; valvd infer- 

 lore plerumque fuUatd ; area ligameiiti magna, ligamento haud 

 tecto ; intus subnacred, limbo lato toto purpure o, sen 

 nonmimquam Jlavcsco-ruhente ; margine extremo ere- 

 be r rime et m inut e crenulato ; dentibus validis ; fossa 

 ligamenti canalibus 2-6 parallelis, decussatis ; muse. imp. sub' 

 orbiculari, magna. 



