580 MOLI/USCA FROM ANGOLA, PORTUGUESE WEST AFRICA. 



Trigonarca cf. ligeriensis (Orbigny). 



Fig. 12. External aspect of summit region, preserved as a limestone cavity, showing the divergently 

 grooved ligament region as well as microscopically fine and closely arranged concentric costa?. crossed by 

 obscure radial striations. From a wax impression. x 2. 



Fig. 13. Natural limestone cast of another specimen, showing internal characters of a right valve, 

 including muscular impressions and teeth. 



Locality:— -N. of Lobito (No. 281). 



Trigonia crenu/ata, Lamarck. 



Fig. 14. External view of a right valve preserved as a limestone cavity, showing the coarsely 

 crenulated costae and the more minute ornamentation of the post-areal surface. From a wax impression. 

 Locality. — Catumbella. British Museum (Ansorge Coll.), L. 18,582. 



Anthonya cf. baudeti (Coquand). 



Fig. 15. View of fragmentary specimen with closed valves, the right being fractured in the summit 

 region and so exposing the dentition of the opposing valve. 



Fig. 16. Enlarged portion of same specimen, showing the two divergent cardinal teeth and minute 

 vertical striations between the closely arranged concentric costae. x 2. 



Locality.— N. of Lobito (No. 286). 



Toucasla sp. 



Fig. 17. Natural internal cast, giving a lateral view of a lower valve with an arched umbonal region 

 and a secondary umbonal structure beneath it with a similar curvature. 

 Locality. — Hanha Gorge (No. 273). 



Tylostoma ghbosum, D. Sharpe. 



Fig. 18. Medium-sized example illustrating the semilunate aperture of this species. 

 Locality. — Lobito ; collected by Mr E. Robins. 



Fig. 19. A giant form of the same species, showing the characteristic irregularity in the suture of the 

 body whorl. 



Locrt/t'/?/.— Catumbella Bridge (No. 100). 



Mrhilaia cf. nerinxformis (Coquand). 



Fig. 20. Front view of limestone cast, showing the excavated faces of the volutions, the deep suture 

 and obscure traces of marginal nodulatidns. 



Locality. — Catumbella. British Museum (Ansorge Coll.), G. 17,024. 



Hipponyx sp. 



Fig. 21. Lateral view of a limestone cast, showing remains of longitudinal striations at the basal margin. 

 Locality.— -N. of Lobito (No. 286). 



Note. — The specimens herewith figured, as well as other portions of this collection, are in course of 

 presentation to the British Museum by Professor Gregory, with the exception of those represented by 

 figs. 14 and 20, which already belong to that institution. 



Plate II. 

 This plate bears its own explanations. 



