84 MR. R. B. NEWTON ON FOSSILS FROM MADAGASCAR. [Feb. 1895, 



cavity having its sides carinated and its terminations slightly 

 produced. C. lyrata and G. pectinata were originally regarded as 

 s?parate species, but a comparison of the types in the Geological 

 Society's Museum has compelled me to unite the two names, being 

 convinced that they are the same. This being the case, I think it 

 best to adopt G. pectinata, as it is much better figured and described 

 than the other, both having been published in the same year. This 

 shell appears to occur quite as abundantly in Madagascar as it does 

 in India (Cutch), and is found associated with Gorbula Grandidieri 

 and Astarte Baroni. 



Dimensions. — Length = 23 mm.; height = 21 mm.; breadth = 

 17 mm. 



Horizon. — Oolite (probably Lower). 



Loc. — About 2 miles south of Andranosamonta village. 



Corbtjla Grandidieri, sp. nov. (PI. III. figs. 15, 16.) 



Shell subglobose, nearly equivalve, inequilateral, subtrigonal, and 

 concentrically furrowed ; posterior area carinated, oblique, and 

 vertically ribbed, containing a narrow and elongate ligamental 

 depression; umbones incurved, contiguous and anterior; the space 

 beneath the umbones is deeply excavated, though without a definite 

 lunule : ventral border curved. Dentition not known. 



Dimensions of the largest example. — Length=32 mm.; height = 

 27 mm. ; breadth = 21 mm. 



This shell is regarded as a new species under the name of Corbula 

 Grandidieri, in honour of the celebrated French naturalist, M. Alfred 

 Grandidier, who has done so much towards the scientific develop- 

 ment of Madagascar. It mainly differs from Gorbula jyectinata, with 

 which it was found associated together with Astarte Baroni, in the 

 absence of sculpture between the concentric furrows, and in having 

 a more prominent and more ornamented posterior area. 



Horizon. — Oolite (probably Lower). 



Loc. — About 2 miles south of Andranosamonta village. 



PsEUDOTRAPEZIUM VENTRICOSUM, Sp. nOV. (PI. III. figS. 9, 10.) 



Shell ovately elongate, equivalve, slightly inequilateral, ven- 

 tricose ; anterior margin short, posterior long ; ornamented with 

 numerous concentric growth-lines rather irregularly set ; ligament 

 external ; the umbones are antero-mesial, contiguous and strongly 

 incurved ; lunule abseat : posterior area obliquely carinated, and 

 enclosing a prominent lanceolate escutcheon depressed beneath the 

 umbones, but becoming afterwards sharply convex. 



Dimensions (valves in contact). — Height=26 mm. ; length = 

 42 mm. ; breadth = 23 mm. The escutcheon measures 25 x 15 mm. 



On account of the strongly carinated posterior margins and its 

 extensive escutcheon-area, this specimen is placed in Fischer's genus, 

 Pseudotrapezium, the type of which is Cypricardia bathonica, 



