Catillopecten eucymatus (Dall, 1898)
DALL, W. H. 1898. Contributions to the Tertiary fauna of Florida. Silex Beds of Tampa and the Pliocene Beds of the Caloosahatchie River. Part IV. I. Prionodesmacea: Nucula to Julia. 2. Teleodesmacea: Teredo to Ervilia. Transactions of the Wagner Free Institute of Science of Philadelphia, 3 (4): viii, 571-947 p., pls. 23-35 (pls. 36 and 37 in part 5, 1900). [p. 754]
1898 Pecten (Hyalopecten) eucymatus Dall, 1898
Catillopecten eucymatus (Dall, 1898) (comb, nov.); H. H. Dijkstra & S. Gofas, 2004, Pectinoidea (Bivalvia: Propeamussiidae and Pectinidae) from some northeastern Atlantic seamounts, figure 15.
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«? Section Hyalopecten Verrill.
Hyalopecten Verrill, Trans. Conn. Acad., x., p. 71, 1897. Type P. undatus Verrill, op. cit., vi., p. 444, 1885; = P. fragilis Jeffreys, Ann. Mag. Nat. Hist., p. 424, 1876, + Hyalopecten dilectus Verr. and Bush, Trans. Conn. Acad., x., p. 80, 1897.
This section differs from the ordinary abyssal Pseudamusium in being concentrically undulated, and from the thin, smooth, shallow-water forms like P. grönlandicus in the absence of the Camptonectes striation. These features are barely of more than specific value, as they appear to be generally interchangeable, like other surface characters in this genus. The types of Jeffreys's P. fragilis are in part in the United States National Museum. They agree perfectly with his description and figures (P. Z. S., 1879, p. 561, pl. xlv., fig. I [inner and outer views]). The first specimens obtained were fragmentary, as was the case with P. undatus Verrill. I have compared the specimens received from both authors with care, and consider them conspecific. P. dilectus is complete, and, except that it is a younger and smaller shell, I have been unable to detect any differences, even of a varietal nature. On the other hand, the specimen to which Professor Verrill has given the name fragilis Jeffreys is a perfectly distinct species with marked characters, as noted by Professor Verrill (op. cit., p. 81). Jeffreys in his original description describes his shell (left valve) as having "numerous fine and raised striae" which "radiate from the beak and cover the whole surface." How, then, Professor Verrill should come to regard a shell "distinctly undulated but not otherwise sculptured" as the species of Jeffreys is a mystery which I cannot solve. At all events, they are perfectly distinct, and the P. fragilis Verrill, non Jeffreys, may take the specific name of eucymatus. It should be observed that the "raised striae," or threads, described by Jeffreys, are more abundant and more constant on the left valve; on the right valve they are often nearly obsolete, and on the left valve the different individuals differ in the amount of their radiation.»
WILLIAM HEALEY DALL, 1898
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