AND MOLLUSCA FROM ANGOLA, PORTUGUESE WEST AFRICA. 573 



Dimensions. — 



Length ...... 40 mm. 



Height . . . . . . 23 „ 



Distribution. — This species is regarded as of Cenomanian age, and has been 

 reported from Algeria, Tunisia, and Italy. 



Occurrence. — The specimen, embedded in a cream-coloured limestone, consists of 

 a pair of united valves in the closed condition showing the external surface of the 

 right, and only the hinge of the other valve being exposed. In the same limestone 

 are examples of Trigonarca cf. ligeriensis, crinoidal stem ossicles, and Nullipore 

 structures. 



Locality. — No. 286 — Plateau N. of Lobito. 



Fam. Cardiice. 



Tr achy car dium cf. syriacum, Conrad. 



Gardium syriacum, Conrad : Lynch's Offic. Rept. United States Exped. Dead Sen, 1852, pi. vii, fig. 45, p. 217. 

 Cardium (Acanthocardia) syriacum, Hamlin: Mem. Mus. Comp. Zoology Harvard, 1884, vol. x, No. 3, 

 pi. iii, fig. 7, p. 48. 



Remarks. — The cream-coloured limestone yielding Trigonarca and other shells 

 contains also some excellent internal casts of Cardium-like valves which closely 

 resemble Conrad's Cardium syriacum from the Cenomanian rocks of Palestine. 

 They possess a narrowly elongate and very much incurved umbonal region, while the 

 surface is furnished with numerous fine and closely arranged radial costse which 

 appear to show obscure traces of minute lateral asperities. 



In contour the valves are subglobose, heart-shaped, somewhat oblique, and of 

 greater height than length. The hinge line is short. Such characters would 

 suggest the inclusion of this species in Morch's genus Trachycardium (type 

 = Cardium isocardia, Linnaeus) rather than in Acanthocardia (type=C. aculeatum, 

 Linnaeus) as suggested by Hamlin, in which the valves are usually longer than high, 

 besides possessing a more extended hinge region. 



Dimensions. — 



Length ...... 25 mm. 



Height . . . . . . 29 „ 



Diameter (with closed valves) . . . 23 „ 



Distribution. — So far as can be ascertained, this species has been hitherto 

 restricted to the Cenomanian (Buchiceras zone) rocks of Palestine. 



Occurrence. — Found in the cream-coloured limestone with Trigonarca, crinoidal 

 stem ossicles, and other remains (No. 281) ; another example occurs with Hipponyx 

 (No. 286) ; and some isolated specimens are in a similar matrix (No. 292). 



Localities.— -N os. 281, 286, 292— Plateau N. of Lobito (281, 286); Canyon E. of 

 Old Lobito (292). 



