COMPLETE GRAU : PECTINIDAE OF THE EASTERN PACIFIC 109 



Chlamys (Plagioctenium) latiauritum [sic] Conrad. Bavay, 1936, p. 



315. 

 Leptopecten latiauratus Conrad. Morris, 1952 [ex parte], p. 16, pi. 1, 

 fig. 3; pi. 5, fig. 4. [Figures = Chlamys (Leptopecten) latiaurata 

 monotimeris (Conrad).] ". . . San Francisco to Gulf of California." 

 Leptopecten latiauratus Conrad. Abbott, 1954 [ex parte], p. 365, pi. 34, 

 fig. i. [Figure = Chlamys (Leptopecten) latiaurata monotimeris 

 (Conrad).] 



Holotype : Academy of Natural Sciences, Philadelphia. 



Type locality : San Diego, California. 



Original description: Shell inequilateral, thin, compressed; ribs 

 fourteen, flattened on the back, slightly sulcated ; interstices transversely 

 striated; ears very wide, unequal, both acutely angulated at the ex- 

 tremity; colour reddish brow^n and white, variegated or spotted. 



Additional Description: Shell rather thin, slightly oblique and 

 moderately convex; equilateral or nearly so; adult specimens averaging 

 20 mm in height and length. Hinge line almost always longer than disk 

 in juvenile stage; in adult stage infrequently longer, usually slightly 

 shorter. Both valves with 12 to 16 rounded ribs (actually corrugations 

 of disk), rather flat on top and occasionally with a central groove; inter- 

 spaces about same width as ribs and in some specimens having one or 

 two low radial ridges ; concentric lamellae covering disk, quite profuse 

 in juvenile stage but less prominent in adult. Anterior auricles longer 

 than posterior, former projecting beyond margin of disk, latter seldom 

 reaching to margin ; anterior auricle of right valve having 4 to 7 imbri- 

 cated riblets, other auricles having 4 to 8 riblets and fine concentric 

 lamellae. Reverse surfaces of interspaces flat and angulated. Colors: 

 red, pink-red, orange, yellow, pale yellow-brown to deep brown, white; 

 usually mottled with white or paler shade of basic color. 



Remarks : Arnold based his subspecies delosi on only two distinguish- 

 ing features: ". . . its extremely long hinge line and prominently lamel- 

 lated interspaces." Since neither feature is uncommon among juvenile 

 specimens of latiaurata, and since Arnold's type measured only 12 mm 

 in height, delosi is here synonymized. 



Arnold (1906, p. 116) commented: "A pair of valves in the U. S. 

 National Museum (No. 96964), from U. S. Fish Commission Station 

 No. 2840, Santa Barbara Islands, is labeled "P. tumbezcnsis Orb." 

 This shell is probably an albino variety of P. latiauritus, having just a 

 touch of color on the interior of the posterior ear of the left valve." The 

 author recently examined that shell and it is unquestionably an albino 



