Dr. F. A. Bather — Eocene Echinoids from SoJcoto. 303 



but the ethmolysian form did not appear, so far as we know, till 

 the Eocene period. These specimens therefore confirm the view 

 that the stratum from which they came is of Tertiary age. More 

 than this it were not safe to say. 



General Geological Conclusions. 



The fossils collected by Captain Lelean had already been de- 

 termined by Mr. Bullen Newton and myself, and the importaace 

 of their discovery recognised, before I learned that attention had 

 previously been drawn by Professor A. de Lapparent ^ to similar 

 fossils collected in the same district by French officers. The 

 following are the main facts recorded by him. 



Echinoids, which may or may not have been of the same age, 

 were collected by the late Captain Pallier near Zinder [450 km. 

 W. of Lake Chad, and about the same distance E. of Sokoto], but 

 have since been lost. Subsequently Captain Gaden collected at 

 Tamaske, 400 kilometres west of Zinder [and apparently not far 

 from Garadimi], a Nautilus allied to N. Lamarclci of the Calcaire 

 grossier, five casts of Nerita (Velates) Schmideliana, belonging to 

 the variety characteristic of the Middle Eocene, and four Echinoids 

 determined by Mr. Victor Gauthier as one Plesiolampas sp. nondescr., 

 one Leiocidaris, badly preserved but clearly of Tertiary age, and two 

 specimens of LintMa "so closely resembling L. Ducrocqui Cotteau, 

 of the Eocene limestone of Saint-Palais (Charente-Inferieure), that 

 it is hard to separate them from it." It appears that the Plesiolampas 

 and Leiocidaris are not well enough preserved to be capable of 

 description ; otherwise Professor de Lapparent would doubtless 

 have included in his paper a recognisable diagnosis. I have, there- 

 fore, thought it advisable to publish a description of the excellent 

 specimens brought home by Captain Lelean. As for the specimens 

 of Linthia, it occurred to me that Mr. Gauthier might have had 

 before him the same species as that found by Captain Lelean and 

 described above as Eemiaster sudanensis. But, for the reasons 

 already given, I am unable to consider our specimens as resembling 

 L. Ducrocqui, or even as belonging to the genus Linthia. 



[Examination of the Tamaske specimens presented by Captain Foulkes necessitates 

 no modification of the preceding remarks.] 



It is therefore interesting to find that, just as the French and 

 English observers in the field independently made similar discoveries, 

 so the paleeontologists of the two countries have independently 

 arrived at similar conclusions, each confirming the other. 



To French observers are also due other recent discoveries, which 

 throw much light on the geological history of the present specimens. 

 The occurrence of Plesiolampas, a genus hitherto unknown outside 

 Sind, suggests a continuous westward extension of the Eocene Indian 

 Ocean ; and this idea is confirmed by an Egyptian fossil of the same 



^ " Sirr les traces de la mer lutetienne au Soudan," C.E. Acad. Sci. Paris, cxxxvi, 

 pp. 1118-1120; 11 Maj^ 1903; and " Sur de nouveaux fossiles du Soudan," tom. 

 cit., pp. 1297-8 ; 2 June, 1903. 



