NO. 1257. A NEW GENUS OF MOLLUSKS— STANTON. 303 
The peculiar interlocking chondrophores ^ will serve to distinguish 
this genus from any described type known to me, making it so distinct 
tliat it is diiEcult to assign it to any of the established families. The 
superficial resemblance of the shell to Ostrea is probably due almost 
entirely to its similar sedentary habit, and its internal features are too 
distinct to permit its reference to the same family. 
The genus Tergiiem ia Tate^ {—Carpenterla Deslongschamps ^ not 
Gray) is somewhat similar externally, but it is attached by the right 
valve, has a long, narrow^, ligamental groove in each valve, and the 
rounded muscular scar is deeply impressed, while the pallial line is 
not visible. This name, Terquemia, was proposed for a few^ species 
of Liassic shells, was afterwards applied, probabl}^ erroneously, to 
several Triassic species, and still more recently to the above-mentioned 
Cretaceous form, which I suspect to be based on an imperfectly pre- 
served specimen of Chondrodonta. 
Some of the internal features of Hlnnltes, especially the pallial line 
and in thin-shelled specimens the faintly marked muscle scar, are 
suggestive of CJwndrodonta. The chondrophore also extends across 
the hinge plate and projects slightl}' beyond it into the bod}' cavity, 
but it is a deep, simple groove in each valve. In the early stages of 
growth the shell has w^ell-marked ears, and in the right (attached) 
valve a byssal sinus, neither of which features has been recognized in 
Cliondrodijiiia. 
The affinities of Chondrodonta seem to be with the superfamily 
Pectinacea, which includes the Spondylidse and Limid^e as well as the 
Pectinidie, Terquemia has usually been referred to the Spondylidse, 
but in Zittel's Grundziige der Paljeontologie, and also in the English 
edition of the same work, it is transferred to the Ostreidfe, without 
good reason, as it seems to me. Judging from figures and descriptions 
only, I would place it at least in the same superfamily with Chondro- 
donta. 
CHONDRODONTA MUNSONI (Hill). 
(Plate XXV, figs. 1-5.) 
Ostrea munsoni Hill, Proc. Biol. Soc. of Washington, VII, 1893, p. 105, pi. xii. 
Hippurites flahell{fer Cragin (in part), 4th Ann. Rept. Geol. Surv. Texas, 1893, 
p. 190, pi. XL, fig. 1 (not pi. XXXVIII, fig. 3). 
Shell attaining a large size, varying in outline from ovate to 
elongate-ovate, and irregularly triangular; beaks inconspicuous, 
slightly deflected laterally, with a variable, usually small, area of 
^This structure has been observed in eight specimens of C. munsoni, five of C. 
glabra, and four of C. joannse. 
' Appendix to Woodward's Manual of the Mollusca, 1867, p. 65. 
'Mem. Soc. Linn, de Normandie, XI, pp. 127-131, pi. xix, figs. 2-11. 
