88 R. BULLEN NEWTON on 



Veneridae, as advocated by M. Cossmann, rather than with Dosinia, where 

 Jukes-Browne had placed it. The species is named in honour of W. Heward 

 Bell, Esq., F.G.S., who is associated with Mr. Kitson as one of the donors 

 of this Nigerian collection to the Geological Department of the British 

 Museum. 



OCCURRENCE. Cutting No. 6. 

 COLLECTOR. Mr. Kitson. 



Callista elongatotrigona, sp. nov. 

 PLATE 9, figs. 1-5. 



DESCRIPTION. Shell small, thin, sub-oval, elongately sub -triangular, 

 inaequilateral, compressed ; anterior side oblique, ovally confluent with ventral 

 margin, posterior side produced, oblique, truncated, obtusely acuminate at 

 ventral angle, ventral margin elongately curved, lunule lanceolate, superficial, 

 ligament groove elongate, very narrow ; surface covered with more or less 

 regular, depressed, smooth, imbricating, concentric costae obtusely angulate in 

 rear, with finer intermittent concentric striations ; hinge small, dental formula 

 in accordance with Callista ; pallial sinus short, broad, obtusely angled ; 

 umbones small, acute, prosogyrous. 



DIMENSIONS. 



Young. Adult. 



Height ... ... ... ii ... 14 millimetres. 



Length 8 ... 21 



Diameter (valves united) ... 6 ... 10 



REMARKS. The few valves representing this species are related to Cytherea 

 laevigata of Lamarck * and C. proximo, of Deshayes, 2 both European shells, 

 the former from the Middle and Upper Eocene, the latter being of Lower 

 Eocene age. From C. laevigata the present species differs in having more 

 cuneate and compressed valves, which are, moreover, less smooth and without 

 any evidence of the fine microscopical radial striations seen in the shelly 

 texture of that species. It differs also from C. proxima in its more cuneate 



1 Ann. Mus. Hist. Nat. (Paris), 1806, Vol. 7, p. 134 ; ibid., 1808, Vol. 12, pi. 21 (40), fig. 5. 



2 Suppl. Desc. Coq. Foss., Paris, 1858, Vol. i, pi. 30, figs. 31-34, p. 435- 



