COMPLETE GRAU : PECTINIDAE OF THE EASTERN PACIFIC 157 



Carpenter had written on the original label "Pecten squarrosus Cpr. 

 Type. 'Sta. Barbara.' Also and really Florida. Jewett." 



In her 1958 paper Palmer discussed Pecten squarrosus and gave her 

 ideas as to the possible identities of the two specimens she designated 

 syntypes, the two right valves Carpenter labelled "Type.'' As Palmer 

 remarked, the left valve he also labelled "Type" must be disregarded, 

 because of his statement that Jewett's valves were dextral. 



Figure 1 on plate 10 of this paper is a photograph of the syntypes. 

 Of the specimen on the left, Palmer said that it ". . . bears a resemblance 

 ... to the holotype of P. acanthodes Dall {in Smith, 1937, pi. 9, fig. 3." 

 Dall (1925b, p. 120) described P. acanthodes and gave the range as 

 ". . . from Southern Florida to the Antilles.", but he did not figure the 

 species; Maxwell Smith figured the holotype, but unfortunately his 

 photograph shows only the interior of the right valve. Judging from a 

 long series of P. acanthodes in the author's collection, this valve of 

 Carpenter's cannot be referred to that species ; it is a specimen of Pecten 

 muscosus Wood (1828, pi. 2, fig. 2; = Pecten exasperatus Sowerby, 

 1842, p. 54, pi. 18, figs. 183-186). P. acanthodes differs from P. mus- 

 cosus in being less convex, at least as long as it is high (often longer), 

 in having posterior auricles of only moderate length, and in having 

 shorter, finer, and more profuse scales, those of the central riblet on each 

 major rib being very little stronger, if at all, than those of the adjoining 

 riblets ; its proper status is that of a subspecies of ?fiuscosus. 



Of the specimen shown on the right in figure 1, plate 10, Palmer 

 said it ". . . bears a resemblance to the holotype of P. heliacus Dall 

 (1925b, p. 119-120) as figured in Maxwell Smith (1937, pi. 9, figs. 5a, 

 5b) . . ." Pecten heliacus Dall is known only by the holotype, which 

 was not figured until Smith reproduced photographs of it ; his figure 5a 

 shows the exterior of the left valve and 5b the interior of the right. 

 Those figures, along with Dall's description, show that this valve of 

 Carpenter's differs considerably from P. heliacus in being more convex, 

 having a larger anterior auricle and a strongly produced anterior auricle 

 (resulting in a much longer hinge margin), and in having wider ribs 

 and different sculpture. Except for the longer posterior auricle and the 

 less orbicular disk, this valve resembles P. acanthodes; it may be a 

 geographical form of P. muscosus, being similar to some specimens of 

 that species in the author's collection. Incidentally, P. heliacus must also 

 be regarded a nomen dubium. It was described from a single specimen 

 sent to Dall by the late shell dealer, Walter F. Webb; the locality 



