116 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 23 



Aequipecten (Leptopecten) velero biolleyi (Hertlein & Strong, 1946). 

 Keen, 1958, p, 70, fig. 131. Port Parker, Costa Rica to Panama. 



Holotype: California Academy of Sciences, San Francisco. 



Type locality : Port Parker, Costa Rica. 



Original description : Shell small, rather thin, hinge long ; color white 

 and brown arranged in concentric bands ; anterior ear of right valve with 

 large byssal notch and ctenolium, ornamented by three ribs ; ventral mar- 

 gin broadly rounded ; left ear large and broadly notched, ornamented by 

 about four ribs; valve ornamented by about 12 to 13 rather high sharply 

 triangular ribs which are separated by considerably wider interspaces, 

 ribs and interspaces with strong, dense, fringing imbricating lamellae; 

 when slightly worn the tops of the ribs are smooth; the ribs near the 

 anterior and posterior margins are somewhat higher than the others and 

 sometimes every third rib or pair of ribs is slightly raised ; left valve 

 similar to right except that it lacks the large byssal notch and the right 

 ear is ornamented by about 4 or 5 ribs and the left ear is ornamented by 

 5 or 6 ribs; on some left valves every third rib is raised higher than the 

 intervening ones. Length, 6.9 mm ; height, 6.6 mm. 



Remarks: From Chlamys (Leptopecten) velero the subspecies differs 

 in having fewer ribs, heavier shell and greater tumidity. The coloring is 

 darker, both valves being medium to very dark brown, with white mark- 

 ings. Fully adult specimens average 8 or 9 mm in height. 



Geographical range: Punta Abreojos, western Lower California, and 

 Gulf of California, to La Libertad, Ecuador. This subspecies had pre- 

 viously been reported only from Banderas and Guatuico Bays, Mexico, 

 Port Parker, Costa Rica, and Guayabo Chiquito Bay, Panama. Collec- 

 tions at Hancock stations extended the northern range by about 800 

 miles and the southern by about 700. 



Geochronological range: Known only from the Recent. 



Bathymetric range: Recorded in 10 to 120 fathoms. 



Ecological data : Found in either sand or mud bottoms. 



Hancock Expeditions Collecting Stations: 

 ECUADOR: La Libertad, 15 fathoms, bottom sample 502; San Fran- 

 cisco Bay, 4-10 fathoms, bottom samples 510, 583. 

 COLOMBIA: Port Utria, 20 fathoms, mud, sta. 233-34; Gorgona Is- 

 land, 10-20 fathoms, bottom sample 584. 

 PANAMA: off Bahia Honda, 30-35 fathoms, sand, mud, sta. 244-34; 

 Secas Islands, 25 fathoms, mud, sta. 250-34; Jicarita Island, 24 

 fathoms, bottom sample 310. 

 COSTA RICA: Port Culebra; 10 fathoms, mud, sta. 253-34. 



