COMPLETE GRAU : PECTINIDAE OF THE EASTERN PACIFIC 55 



the pectinidial teeth are small and few. The byssus is probably very 

 slender. The auricles are not oblique and are nearly equal. The hinge- 

 plate is very thin ; the single longitudinal ridge is scarcely visible, 



A row of six or seven ocelli can be seen through the shell in alcoholic 

 specimens. (Verrill & Bush, 1898.) 



Remarks: Sowerby, in using the term "aequivalvi," was more nearly 

 correct than Verrill, as quoted above, for the right valve is only occa- 

 sionally larger than the left. 



The author recently examined "co-types" of Pseudamusium andersont 

 Dall (= Pecten binominatus Hanna) and found that they are actually 

 specimens of Cyclopecten greenlandicus. As can be seen from the range 

 given below, C. greenlandicus is not an eastern Pacific species ; under the 

 names Pseudamusium andersoni or Pecten binominatus, however, it has 

 appeared in works on the fauna of the region and therefore is included 

 in this paper. 



An author's original spelling must be preserved, unless a lapsus 

 calami or misprint is evident, but from Sowerby 's time to the present 

 the only writers who followed his spelling were Forbes & Hanley (1853, 

 p. 294). 



Geographical range: Arctic Ocean, except Chuckchee (Chukotskoe) 

 Sea (NW of Bering Sea). Eastern Atlantic: Iceland, west Norway, 

 Faeroe Islands, Hebrides Islands, west and south Ireland, Bay of Bis- 

 cay, Gibraltar, Azores and northwest Africa. Western Atlantic: Green- 

 land to Gulf of St. Lawrence. 



Geochronological range : Pleistocene, Recent. 



Bathy metric range: Recorded in 5j^ to 1785 fathoms. 



Ecological data: Little available, but apparently always found in 

 mud. 



Subgenus HYALOPEGTEN Verrill 1897 



Hyalopecten Verrill, 1897, p. 71. [Proposed as a genus.] Type species: 

 Hyalopecten dilectus Verrill & Bush in Verrill, 1897, p. 80; type 

 locality: Albatross station 2570, off Martha's Vineyard. Massachu- 

 setts, in 1813 fathoms.— Verrill & Bush, 1898, p. 836, pi. 97, fig. 

 9. [Synonyms {fide North, 1951, p. 234) : Pecten fragilis Jeffreys, 

 1879, p. 561, pi. 45, fig. 1 ; non P. fragilis Def ranee, 1825, p. 251 ; 

 non P. fragilis Jeffreys, 1876, p. 424 (^ P. biscayensis Locard, 

 1888, p. 272). Pecten undatus Verrill & Smith, 1885, p. 444, pi. 

 44, fig. 21 (designated type species by Verrill, 1897, p. 71) ; non 

 P. undatus Def ranee, 1825, p. 257.] 



