Nigerian Eocene Molhisca. 47 



periphery, while all the volutions have depressed sides. Each whorl bears 

 about 1 2 robust, longitudinally oblique costse which are slightly excavated or 

 bent backwards, being thickest anteriorly, and separated by wide furrows. 

 The whorls likewise bear strong, closely-set spiral ridges (about 1 2) which in 

 passing over the summits of the costse set up depressed tubercled thickenings 

 forming a more or less scalloped margin to the suture, the spiral ridges 

 divided by sulcations of corresponding width are continued over the basal 

 surface of the last whorl. The columella is excavated and smooth while the 

 aperture exhibits an ovate contour, although the labrum and other essential 

 characters of the basal whorl are not preserved. 



DIMENSIONS (fragmentary specimen). 



Length .. ... ... ... ... 50 millimetres. 



Diameter ... ... ... ... ... 20 ,, 



REMARKS. This strikingly ornamented shell which is the only example in 

 the collection is so imperfect at both ends that its position even generically 

 is somewhat uncertain. Its reference, however, to Terebralia appears to be 

 justified on account of its shape and sculpture, while certain erosive agencies 

 are evident on the earlier part of the spire which would indicate a former 

 existence spent in more or less brackish waters. Rather similarly marked 

 shells are known in the latest Cretaceous of Egypt, Dr. J. Wanner having 

 described and figured one as Cerithium dachelense ( Palaeontographica, 1902. 

 Vol. 30, part 2, p. 130, pi. 1 8, figs 25-28) which he regarded as being related 

 to J. de C. Sowerby's Cerithium corrugatum from the Nummulitic Beds of 

 Western India (Cutch) and since recognised in Archiac's memoir as C. 

 pseudocorrugatiim of Orbigny (Archiac & Haime, " Desc. Anim. Foss. Nummu 

 Htique Inde," 1853). Both the Cretaceous and Tertiary species here mentioned 

 bear somewhat similar vertical costae but they are more irregular being 

 interrupted by occasional varices which are not present in the Nigerian shell. 

 Again, a certain agreement in sculpture may be observed on some forms 

 from the Ronca beds of Italy as originally described by Brongniart especially 

 his Cerithium multisulcatum, and which are of Upper Lutetian age. (Me'm. 

 Terr. Calc.-Trapp. Vicentin, 1823, pi. 3, pp. 67, 68). 



OCCURRENCE. Cutting No. 10. 

 COLLECTOR. Mr. Kitson. 



