140 TERTIARY AND QUATERNARY PECTEHS OF CALIFORNIA. 



Pecten (Pseudajiusium) vancouverensis AA'hiteiives. 



PI. LII. (igs. :! ;iih1 .^i. 



1S8(). Pecten caui-bias Dall (not Gould), Bull. Miis. Com].. /,.... 1., vol. 12, ]88fi, p. 21(i, pi. 5, fig. 4 

 (.supposed young of P. rminnun). 



18S7. Peiien {Pseudaiininiuiii) Ahtshennix Whiteave!^ (not 1 tall ), Trans. Roy. Soc. Canailu, Mil. 4, sec. 

 4, for 1886, 1887, j). 119. 



1889. Pecten caurinus Dall (not (ioul.l), Hull. l'. S. Nat. Mus., No. 37, 1889, pi. ."1, tit;. ■+ (supposed 

 young of P. caurinus). 



189:5. I'erten (Pseudanmshmi) Vwicouverenaix Whiteaves, Ottawa Naturalist, vol. 7 (l)eiiig vol. 9, 

 Trans. Ottawa Field-Nat. Club), 1893, p. 133, pi. 1, ti^a. 1, \<i. 



1893. Pecld'n (Pseadamunhmi) ]'(incoiirerr)i.'ii.<t Whiteaves, Newconibe, Bull. Nat. Hist. Soc. Brit. Co- 

 lumbia, 1893, art.. 5, p. 53. 



189.">. i'erlen (Ptendainufiiiuii) I'lmcdtiirniisis Whiteaves, Taylor, Trans. Roy. Soc. Canadn, L'd ser., 

 vol. 1, 1895, sec. 4, p, 2(i. 



1904. Pecten trincoiirereri.-il.'i Whiteaves. Kee]i, West Am. Shells, ]i. 41. 



The oiigiiiul de.scriptioii is us I'ollow.s: 



Descripthin. — "Sliell small liiveraging- about T.o niillinieter.s in altittidcj. ('(|iii 

 Viilved, compressed leiitii'idiii'ly. hoth valves lieiiio- e(|iially convex, ovatelv suhcircu- 

 lar in outline apart from the ears and rather ohliciue; valves extremely thin and 

 fragile, translucent and almost transparent, pale horn color with a slightly yellowish 

 hue. Beaks placed a little behind the midlength; hinge line straight and very long; 

 ears unequal in size, the posterior pair, which are much smaller than the anterior, 

 alike, indistinctlj' defined, and merging gradually an<l imperceptibly into the general 

 con\exity and marginal contour of that side of (nich \alve: anterior ears large, sub- 

 triangular, prolonged lutcridly. and longer than high, distinctly defined, that of the 

 left valve somewhat convex in outline above and concave below, that of the right 

 valve with a deep and ticutcly angular byssal sinus at its V)ase. 



"' Surface marked by densely crowded and exceedingly minute, irregular, and 

 rarely contimious, but, on the whole, radiating, simple or bifurcating raised lines, 

 also by comparatively large, regularly disposed, and distant sijuamose rtidii. In the 

 center of each \alve the minute and nonsquamosc 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 miiuitt'ly 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 l)e clearly seen without the aid of a microscope or powerfid simple lens, 

 l)ut luider either of these a few faint concentric lines of growth are also visible." 



Dimensions. — Alt. 7.5 mm.; long. 7.75 mm.; diameter 2.25 mm. 



This beautifid little IWicn is easily distinguishable from the other members of 

 the same group by its smaller size when adult, fine radiating lines of sculpture 

 externallv. and bv its relativelv longer hinge line. 



Living. Sitka Harbor, 12 fathoms (Dall); Forwiirfl Inlet, Quatsino Souiul (Daw- 

 son); Departure Bay (Taylor, Macoun): ofi' San Pedro, Los Angeles County, 

 200 fathoms (Oldroyd); Avalon Harbor, Catalina Island, 15 fathoms (Arnold). 



