Nigerian Eocene Mollusca. 19 



aperture narrow, semi-circular, with short, broad, canaliculated ends ; labrum 

 widely reflected with slightly divergent, tapering ends, ornamented with strong 

 horizontal ridges continued from dorsal surface, without intermediate vertical 

 striations, inner ridges forming equi-distant, marginal serrations ; columella region 

 elongately ventricose, constricted and tapering at the ends, posterior end coarsely 

 and obliquely ridged, internal margin with minute, equi-distant denticles formed 

 of the thickened terminations of the horizontally ridged sculpture. 



DIMENSIONS. 



Alt. ... ... ... ... ... ... ... 19 millimetres. 



Lat ii 



Depth ... ... ... ... ... ... ... 9 



REMARKS. This shell is placed in the genus Amphiperas of Gronovius 

 1781 (= Ovula Bruguiere, 1789, established on the type of Bulla ovum, 

 Linnaeus), on account of the absence of any external evidence of a spire, 

 together with its possession of short and broadly canaliculated extremities, and 

 the elongately oval contour of the columella region. In its ornamentation there 

 is greater agreement with Swainson's Cypraedia of 1840 (Type = Cypraea 

 elegans, Defrance Eocene, France), and rather less so with Cypraeovula of 

 Gray (Type = Cypraea capensis, Gray of Recent Seas), both genera belonging 

 to the true Cypraeidae, a family which invariably exhibits in the posterior region 

 some external indication of the presence of a spire. In both these genera also 

 the posterior end of the labrum curves towards the summit region, whereas in 

 Amphiperas the extremities on both sides of the aperture are more or less 

 vertically extended and open. When writing " On the Relations of the 

 Amphiperasidae," Dr. T. Gill x has stated that the members of that Family 

 " have not even spiral shells, the testaceous envelope being simply a shell loosely 

 rolled on itself, and more or less attenuated and twisted at the extremities." 

 Such remarks apply to the present specimens from Nigeria although differing 

 from the smooth surfaced type of Amphiperas in being horizontally ridged 

 throughout and possessing a columella-margin with equi-distant denticles formed 

 of the delicately thickened edges of the ridges. This species is represented 

 by a number of examples. 



OCCURRENCE. Cuttings Nos. i, 5, 6, 10, n, 12, 13, 14, 15. 

 COLLECTOR. Mr. Kitson. 



1 American Journ. Conch. 1870-71, Vol. 6, pp. 183-187. 



2* 



