186 CRETACEOUS PELECYPODA 



the pallial impression, of which no notice is taken in the characteristics given. In 

 the figure of the right valve it would seem as if a deep pallial sinus were indicated, 

 in the left valve everything is quite confused. 



Clienu (Man., ii, p. 97,) copies Paujas' original characteristic, or rather 

 Philippi's (Handb., p. 319), who says that the ligament is external; the same 

 author quotes a species Clotho Faujasii, but the hinge of the right valve figured 

 by Chenu appears to show considerable difference from that of the original 

 species of Clotho; the form of the two shells also does not agree. I do not 

 know where to find an explanation for this discrepancy ; possibly the former may 

 be a different species, or is it only one of the many wrongly copied figures of fossil 

 shells in Chenu' s Manual ? 



4. Coralliophaga, Plain., 1824. Shell elongated, sometimes sub-cylindrical, 

 of a more or less thin structure ; hinge with two compressed cardinal and one 

 lamellar posterior lateral tooth, all teeth being more or less parallel to the superior 

 margin of the valves ; pallial sinus generally with a small broad sinus. 



5. Trapezium, M. v. Mlihlf., 1811. Shell trapezoid, solid, usually with a 

 characteristic radiating striation on the surface ; hinge with three more or less 

 regularly diverging cardinal teeth, the anterior in. the right and the posterior 

 tooth in the left valve being the smallest, the middle one in the right valve the 

 largest, and the posterior one usually bifid ; posterior lateral tooth lamellar and 

 parallel to the superior margin; pallial line entire, truncated posteriorly. The 

 two anterior cardinal teeth in the left valve are sometimes united by a low ridge, 

 forming so to say one elongated curved tooth, which is, however, more curved than 

 in Veniella, but considerably less than in Venilicardia. 



6. IsoGulia, M^Coy, (?) 1844. Under the name of L ventricosa, M^Coy 

 figures (Carb. limestone fossils of Ireland, pi. 13, fig. 3), a very tumid, cordate 

 shell with a few concentric distant constrictions, indicating stages of growth. The 

 shell appears perfect and closed ; I have not been able to find any further reference 

 to this shell in this or any other work. Possibly it may be an JEclmondia, or a 

 Cardiomorpha, for on pi. 8, fig. 15, of the same work is also a species noted as 

 IsoGulia Gorrugata, but in the text (page 56) referred to as a Cardiomorpha. 



7. Callocardia, A. Ad., 1864, (Ann. Mag. Nat. Hist., xiii, p. 307). Shell 

 cordate and inflated like in Olossus, posteriorly scarcely flexuous, thin and 

 without epidermis ; hinge of the left valve with two unequal cardinal teeth ; the 

 anterior angularly bent on itself in the middle with a triangular pit on either 

 side and with four prominent cusps at the margin ; the posterior oblique, curved, 

 narrow, but elongated, and with two indistinct marginal cusps ; no lateral teeth 

 are present ; pallial line simple and muscular impressions semi-lunar. 



There is as yet only one (left) valve of this remarkable species, O, guttata, 

 known from the Chinese seas. The absence of the posterior lateral tooth, as well 

 as the peculiar cuspidation of the two hinge-teeth, distinguish it readily from 

 Glossus or Veniella f= Venilia, Morton^ subg. AnisoGardiaJ, but the form of the 

 angularly bent '' anterior" cardinal tooth undoubtedly strongly recalls GlossoGardia, 



