MUSEUM OF COMPARATIVE ZOOLOGY. 257 



When 1 first received these valves I supposed that they would turn out to 

 be identical with some one of Conrad's Tertiary species; but after comparing 

 with them all, I found that none of them agreed sufficiently well with the re- 

 cent species to render it desirable to refer it to either of them. The nearest 

 of the fossil forms to the C. fioridana is the C. undulata Conrad (not Sowerby), 

 of the variety figured by him on Plate XI. of his Fossils of the Tertiary For- 

 mations of the United States, which (though dated 1838 on the title-page), ex- 

 cepting the first few pages, was not issued until 1845. From this C. fioridana 

 differs in being more pointed anteriorly and less so behind; in having flatter 

 and less pointed beaks ; in having a more pronounced flexure below the ros- 

 trum, and the latter proportionately shorter, higher, and more ridged above ; 

 the cardinal teeth are more oblique, and the anterior lateral does not run up 

 in front of the cardinals, but ceases near their lower extremity. I find these 

 differences to hold good through a large series, and consequently conclude that 

 the recent species is distinct. It is entirely different from the C. antillarum, 

 until now the only recent species of Crassatella proper known to inhabit the 

 Antilles. 



The margins of C. fioridana are smooth at all stages, but the outside grooving 

 in aged specimens becomes obsolete near the margin. 



Subgenus ERIPHTLA Gabb. 



Eriphyla Gabb. Pal. Cal., I. p. 180, 1864 ; Stoliczka, Pal. Indica, III. p. 156, 1871 

 (but not pp. 181, 182, pi. \i.; = Dozia Bosquet, 1868). Type E. umbonata 

 Gabb. 



Eriphylopsis Meek, Inv. Pal. Upper Missouri, p. 125, 1876. Type E. gregaria Meek 

 and Hayden. 



The genus Eriphyla of Gabb was poorly figured, and hastily, or at least 

 imperfectly, described by its author, for whom, however, allowance should be 

 made on account of his isolated position in California, far from well-equipped 

 museums or libraries. Meek, who was one of the most careful and exact 

 paleontologists, examined into the subject, and found that there could be little 

 doubt that the differences between the type of Eriphyla and the small Crassa- 

 telloids formerly included under Gouldia, and best known by that name (and 

 for his purposes best typified by C. mactracea Linsley), were essentially these. 

 The teeth appeared to be reversed as regards the valves, and there was a little 

 furrow behind the beaks which by Gabb and himself was supposed to indicate 

 the presence of an external ligament, the internal cartilage when absent, as 

 in dead valves or fossils, leaving no evidence of its existence. In 1871 Sto- 

 liczka complicated the problem by referring to Dozia lenticularis Goldfuss as 

 the type of Eriphyla ; and by describing that group from the peculiarities 

 of the aforesaid Dozia (which probably belongs near Dosinia). This error 

 has been copied from Stoliczka into Tryon's Structural and Systematic Con- 



VOL. XII. — NO. 6. 17 



