Nigerian Eocene Mollusca. 51 



terminations and possessing nine whorls measures 27 millimetres, while a 

 disconnected basal whorl has a diameter of 9mm. They belong to an 

 elongately narrow, imperforate shell which had probably about a dozen 

 volutions of gradually increasing growth, showing considerable convexity, and 

 divided by a deep suture. The ornamentation consists of prominently elevated, 

 well separated, longitudinal costae with terminal curvatures at the suture, the 

 intervening furrows being strongly and transversely striated. The basal disc 

 has a well defined spiral carination which encloses a floor decorated with well 

 marked radial and concentric sculpture. In most of these characters a 

 relationship is traceable to the European species, Acrilla affinis, which 

 M. Cossmann refers to the Upper Eocene, although the Nigerian shell is 

 probably a narrower type with less gradually increasing whorls. A further 

 closely related form is Scalaria multilamella, Deshayes (Desc. Coq. Foss, 

 Paris, 1832, Vol. 2, p. 196, pi. 22, figs. 15, 16), which on account of that 

 specific name having been used at an earlier date by Basterot, for another 

 shell, has been re-named by M. du Boury as Acrilla gallica (Desc. Scalidae 

 Nouveaux Eocenes, Paris, &c., 1887, p. n), a form, however, with less 

 elevated and more numerous longitudinal lamellae. 



DISTRIBUTION. Upper Eocene, Europe. 

 OCCURRENCE. Cutting No. 6. 

 COLLECTOR. Mr. Kitson. 



Family XENOPHORID^. 



Tugurium nigeriense, sp. nov. 



PLATE 4, figs. 20, 21. 



DESCRIPTION. Shell small, of conically spreading form, composed of 6 or 7 

 depressed whorls the earliest of which (4 or 5) are rounded, smooth, obtusely 

 apexed, and divided by a well marked regular suture, the remaining whorls 

 being irregularly sutured on account of peripheral angulation ; base umbilicated 

 but cavity partially covered by a thin columella callosity ; ornamentation of 

 the upper surface consisting of strong spiral ridges and rather finer radial 

 striations, basal region also spirally costated and furnished with radial and 

 well excavated lines of growth producing reticulation ; umbilical cavity deep 



