42 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 23 



non-squamose raised lines are essentially parallel to the larger squamose 

 radii, but on the sides the former are disposed obliquely to the latter. 

 The surface of the anterior ear of each valve is minutely cancellated 

 with extremely minute raised lines, which are almost parallel to the 

 hinge line, in addition to the coarser cross lines. The whole sculpture 

 of the exterior of the test is far too minute to be clearly seen without 

 the aid of a microscope or powerful simple lens, but under either of 

 these a few faint concentric lines of growth are also visible. 



Dimensions of the only specimen that the writer has seen: height, 

 from beaks to base, 7.50 mm. ; maximum length 7.75 mm. ; greatest 

 thickness through the closed valves, 2.25 mm. 



Forward Inlet, Quatsino Sound, Vancouver Island, in ten to twenty 

 fathoms mud. Dr. G. M. Dawson, 1885: one living specimen. 



Additional descriptive notes: Although not mentioned in Whiteaves' 

 very thorough description, a ctenolium of 3 to 6 teeth is present. Many 

 specimens have shallow concentric undulations of the umbonal portion 

 of the disk. On some specimens the squamose sculpture is almost absent 

 and the radii more prominent. Very young shells are frequently nearly 

 smooth. Whiteaves' phrase, ". . . pale horn color with a slightly yellowish 

 hue." is misleading, for when specimens are washed they are devoid of 

 color. 



Remarks: The squarish angle of the posterior auricles and the longer 

 hinge line distinguish this species from the related Cyclopecten randolphi 

 and C. randolphi tillamookensis, the presence of sculpture on the disks 

 also separating it from the former. 



Geographic range: Bering Sea to southern end of Lower California, 

 Mexico, and north in the Gulf of California to San Ildefonso Island, 

 26° 33' 30" N. Previous records indicated San Diego, California, to be 

 the southern limit, hut the species occurred at Hancock stations in Dewey 

 Channel and off the San Benito Islands, western Lower California, and 

 off San Ildefonso Island in the Gulf. 



G eochronological range: Recent only. 



Bathymetric range: 10 to 210 fathoms (rarely less than 50). 



Ecological data : Usually on mud or sand bottoms, occasionally rock, 

 shale or gravel ; often attached to calcareous algae ; often associated with 

 brachiopods, crinoids, coralline or sponge. 



Hancock Expeditions Collecting Stations: 

 WESTERN LOWER CALIFORNIA: 9 stations; 55-81 fathoms, 



gravel or sand. 

 SOUTHERN CALIFORNIA and SANTA BARBARA ISLANDS: 

 49 stations; 23-210 fathoms, rock, sand or mud. 



