BIVALVIA. 19 



became attached by the exterior of the shell, but always preserve their regularity or 

 partial freedom. The exterior of the shells in this Genus have not the regularly 

 radiating form of striae or costae, so characteristic of the Pectens or fans, but they are 

 ornamented with arched or lamellated fringes or squamose appendages, more re- 

 sembling the exterior of Spondylus, to which they appear to have considerable affinity, 

 and, indeed, may be considered as a connecting link between Ostrea and that Genus, 

 differing from the former in having distinct auricles in the young state, and in adhering 

 by a different valve ; and from the latter, in the absence of those dental characters 

 prominently exhibited in Spondylus. 



A few species only are at present known, and those all in a fossil state ; two or 

 three are peculiar to the Tertiary Formations, and one has been figured by Mr. Sowerby 

 in ' Min. Conch.,' from the Inferior Oolite of this country. 



1. HiNNiTES Co-RT^SYi, De Frmice. Tab. III. 



HiNNiTEs CoRTESYi. Be France. Diet, des Sci. Nat., t. 21, Art. Hiuuites, p. 169, Atlas, 

 fig. 1, la, 1821. 



— —Be Blainv. Malac, pi. 61, fig. 1, 1825. 



— — Besh. 2d edit. Lam., torn, vii, p. 150, 1836. 



— — Chenu. III. Conch. Hinnites, pi. 1, fig. 4. 



— CoRTESiANUS. Be Blainville. Die. des Sci. Nat., t. 32, 311, 1824. 



— DuBUissoNi. J. Soioerby. Min. Conch., t. 601, 1829. 



— — Woodward. Syu. Tab. of Org. Rem., p. 20, 1830. 



— — Id. Geol. of Norf., p. 44, 1833. 

 HiNNUS DuBUissoNi. J. Soiv. Syst. Ind. to Min. Conch., p. 244, 1835. 



— — S. TFood. Catalogue, 1840. 



— — /. Morris. Catal. Brit. Foss., p. 110, 1843. 



Spec. Char. Testa magna, ovatd, depressd, crassd, radiafim et undid at ini costatd ; 



iransversim sqiiamosG-lameUosd; auricidis incequalihus ; sulco cardinali,pr(elon(/o, et profimdo. 



Shell large, ovate, depressed, thick, and strong, with radiating and undulating costae ; 



ribs covered with squamose projecting lamellse ; auricles unequal ; and a deep and 



elongated sulcus for the ligament. 



Length, 5 inches. Height, 6 inches. 



Localitg, Cor. Crag, Rarasholt. 



Although a shell of great strength and soHdity, it is by no means abundant as a 

 British fossil, and I have seen it only from one locality, and that in the Coralline Crag. 

 The specimen now figured was from a less disturbed part of that deposit, where the 

 two valves of many of the Bivalvia are found in their natural position ; while the one 

 figured in ' Min. Conch.' was from a single valve. A few other specimens were 

 obtained by W. Colchester, Esq., from the same spot, and these constitute all that 

 I have as yet seen. 



A perfect representation of the Genus Pecten is exhibited in the young shell, and 

 it must then have been difficult to have pointed out a character by which it could be 



