FROM TANGANYIKA AND KENYA 169 



ted. His " var. canina " from the Dogger (? Upper Lias, Yeovilian) of Blea Wyke, 

 Yorks, has eight spirals and much resembles the small shell now recorded. In 

 Germany Quenstedt's species is particularly characteristic of the " Brown Jura a" 

 but ranges up into the " Brown Jura fi " (both Aalenian), and, according to Brosam- 

 len, most specimens have six spirals. The age of the specimen now recorded (Toar- 

 cian) is slightly earlier than that of any recorded European occurrence of the species. 

 The specific name opdlina, under which Quenstedt described this form in 1856, was 

 a homonym, but his emended name opalini, published in 1882, may be adopted. 



Subclass OPISTHOBRANCHIA Milne Edwards 



Order ENTOMOTAENIATA Cossmann 



Superfamily NERINEACEA 



Family NERINEIDAE Zittel 1873 



Genus COSSMANNEA Pchelintsev 1927 



Cossmannea hennigi (Dietrich) 

 PI. 30, fig. 7 

 1904. Nerinea Hennigi Dietrich : 134, pi. 12, fig. 6, pi. 13, figs. ^a-c. 



Material. Two specimens (nos. G. 48914, G. 48917). 



Localities and horizon. Bed of Maimbwi river, and along upper part of 

 tributary to same river, near Tendaguru, Tanganyika ; Upper Kimmeridgian, 

 " Trigonia smeei " Bed and slightly below it. 



Remarks. The generic name Cossmannea is applicable to the group of species 

 designated as Nerinea s.str. by some previous writers, who ignored the fact that the 

 type-species of Nerinea should properly be taken as N. mosae Deshayes. This group 

 is characterized by concave whorls, a bulging sutural region, the presence of 2-3 

 internal folds, and the usually relatively large size of the shell. 



In C. hennigi the concavity of the whorls is only moderate and no tubercles are 

 present on them. There are three strong internal folds. There is a close external 

 resemblance to Cossmannea desvoidyi (d'Orbigny) (Cossmann 1898 : 56, pi. 5, figs. 14, 

 21) which ranges from the Upper Oxfordian to the Tithonian in Europe. C. desvoidyi 

 however, has only two internal folds and is slightly more slender. The maximum 

 diameter of the largest specimens of C. hennigi now recorded is 29 mm. 



Genus NERINELLA Sharpe 1850 

 Nerinella }rnuelleri Cox 



1900. INerinea Credneri Miiller : 537, pi. 17, figs. 11-13 (non Alth 1873, nee Zittel 1873). 

 1954. ?Nerinella muelleri Cox : 16. 



Material. One specimen (no. GG. 10339). 



