92 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 23 



of California, and Clarion Island, to Panama and the Galapagos 

 Islands. "?Santa Catalina Island, California." 

 Chlamys lowei (Hertlein, 1935). Keen, 1958, p. 72, fig. 133. "The 

 Gulf of California to Panama, . . ." 



Holotype: California Academy of Sciences, San Francisco. 



Type locality : Carmen Island, Gulf of California, in 20 fathoms. 



Original description : Shell moderately small, nearly equivalve, 

 higher than long. Right valve w^ith the exterior surface ornamented with 

 20 to 22 roundly triangular ribs; the ribs are crossed by strong imbri- 

 cating lamellae which are fused to form a row of spinose nodes on top 

 of each rib ; toward the ventral margin traces of small riblets appear on 

 each side of the major ribs about halfway between the tops of the ribs 

 and the bottoms of the interspaces; interspaces narrower than the ribs 

 and in each, a spinose riblet is present. Ears unequal, the anterior ear 

 large, ornamented by about four to five riblets which are crossed by 

 imbricating spines; a distinct byssal notch is present and a ctenolium 

 consisting usually of four to five spines ; posterior ear very small and 

 ornamented by four to six spinose riblets. Left valve ornamented similar- 

 ly to right ; anterior ear with eight to ten spinose riblets, while on the 

 posterior ear there are four to six riblets. The color in the living shells 

 is generally gray toward the umbos flecked with brown spots, but grading 

 to brown toward the ventral margin. Some specimens are reddish or 

 orange brown. Type specimen, altitude 13.8 mm.; longitude 11.5 mm.; 

 diameter of both valves 4.5 mm. 



Additional descriptive notes: Further collections of this species 

 have shown that the holotype was an adolescent shell. Hertlein remarked 

 (1946, loc. cit.), "One of the largest specimens in the present collection 

 measures approximately 18.5 mm. from beak to base." The present 

 writer's collection contains a specimen from Clarion Island measuring 

 23.5 mm in altitude, probably the maximum size for the species, or very 

 near. 



Geographical range: Santa Catalina Island, California, to La 

 Plata, Ecuador, including Guadalupe Island (180 miles west of central 

 Lower California), and the Gulf of California, Also Galapagos Islands. 



Hertlein's questioning references to Santa Catalina Island resulted 

 from the occurrence of a left valve in 30 to 80 fathoms. Location 25610, 

 California Academy of Sciences. A single valve cannot be accepted as 

 definite proof of habitation, but at Hancock station 1155-40, off White 

 Cove, Santa Catalina Island, a complete specimen and a right valve 

 occurred among material dredged in 16 to 35 fathoms. In addition to 



