114 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 23 



Original description : Shell thin, orbicular, compressed, equilateral, 

 white to yellowish-brown, with concentric or zigzag narrow bands or 

 flecks of dark rose color; 15 strong ribs rounded in the young, mesially 

 keeled and longitudinally threaded in the adult, separated by narrower 

 channelled interspaces, each with a mesial thread ; all crossed by lamel- 

 lose, concentric, rather sparsely distributed elevated lines; submargins 

 and ears closely radially threaded with imbricated threads. Both valves 

 similarly sculptured; alt. 47.5, lat. 53, diameter about 20 mm. 



Additional descriptive notes: Hinge line slightly more than Yz 

 length of disk; anterior auricles slightly longer than posterior, that of 

 right valve having 4 to 6 strong radial riblets crossed by concentric 

 lamellae, a sharp, narrow byssal notch and a ctenolium of 5 or 6 teeth ; 

 mesial threads in interspaces occasionally absent ; reverse surfaces of 

 interspaces flat and angulated ; prominent crura at base of each posterior 

 auricle. Color range including red, rose-pink, red-brown, yellow-brown, 

 yellow-white and white ; banded and blotched. 



Geographical range: Known only from the Gulf of California; 

 unique in that respect, being the only species of Pectinidae so restricted. 



Geochronological range: Recorded only from the Recent. 



Bathy metric range: On rocks at low tide, and to 50 fathoms. 



Ecological data: Found on rock, sand, sandy mud or mud bottoms. 



Hancock Expeditions Collecting Stations: 

 GULF OF CALIFORNIA: 7 stations; Concepcion Bay north to San 

 Felipe Bay; 2j4 to 45 fms., rock, sand. 



Ghlamys (Leptopecten) velero (Hertlein) 1935 



Plate 37 



Pec ten (Leptopecten) velero Hertlein, 1935, p. 316, pi. 19, figs. 13, 14. 



Bahia Honda, Veragua, Panam.a; Mazatlan, Mexico; Maria 



Madre Island, Tres Marias Group, Mexico. — Hertlein & Strong, 



1946, p. 60. Mazatlan, Mexico to Panama. 



Aequipecten (Leptopecten) velero (Hertlein, 1935). Keen, 1958, p. 



70, fig. 130. Mazatlan, Mexico to Panama. 

 Leptopecten velero Hertlein 1935. Soot-Ryen, 1957, p. 5. "Puna [Gulf 

 of Guayaquil, Ecuador], 8 fathoms, 3 right and 2 left valves, 

 maximal length 16.8 mm, height 16.5 mm." 

 Holotype: California Academy of Sciences, San Francisco. 

 Type locality : Bahia Honda, Veragua, Panama, in 3 to 9 fathoms. 

 Original description: The type is a left valve with 16 strong ribs, of 

 which every third rib is higher than the intervening ones; the two ribs 



