Nigerian Eocene Mollusca 33 



DIMENSIONS. 



Alt 77 millimetres. 



Lat. ... ... 23 



REMARKS. This species of which there are only five examples is closely 

 related to Micrex noae of Chemnitz from British and European Eocene deposits, 

 the type of Dr. Grabau's 1 genus Rhopalithes. It differs, however, in the 

 absence of a sutural platform, having no posterior canal, possessing a generally 

 narrower axis with rather more inflated whorls which are slightly excavated 

 posteriorly, while the sculpture of the later volutions is of a more micro- 

 scopical texture without any strong spiral striations the sinuated longitudinal 

 lines being more apparent than those running transversely. The features of 

 the earlier portion of the spire are similar to those observed in R. noae showing 

 equally well the smooth, depressed protoconch and the four or five succeeding 

 whorls marked by strong equi-distant swollen costae crossed by fine spiral 

 striations. A fractured specimen shows the presence of a single oblique 

 plication on the internal surface of the columella, there being usually two of 

 these in the European species. 



OCCURRENCE. Cuttings Nos. 6, 10. 

 COLLECTORS. Sir F. Lugard ; Mr. Kitson. 



Family STREPTURID/E (Cossmann). 

 Strepsidura spirata, sp. nov. 



PLATE 3, figs. 24, 25. 



DESCRIPTION. -Shell pyriform, excavated antero-laterally ; spire widely 

 coniform, slightly elevated, comprising 5|- depresso-convex whorls, divided by 

 a canaliculated suture, protoconch consisting of 2^- smooth whorls with an 

 obtuse summit ; body-whorl elongate, inflated posteriorly, laterally excavated 

 below, about four times the length of the spire, labrum arched, excavated 

 below, serrated at margin, submarginally thickened and dentated within ; 

 aperture elongately oval, and contracted below into a narrowly elongate, 

 recurved canal ; columella with slight callosity, bearing four or five contiguous 

 spiral ridges succeeded by a thick oblique plication and a twisted funiculate 

 extension to the mouth of the canal ; surface, excluding the protoconch, 



1 Phylogeny of Fusus and its Allies ; Smithsonian Miscell. Coll., 1904, Vol. 44, No. 1417, p. 135. 



3 



