i 7 o JURASSIC BIVALVIA AND GASTROPODA 



Locality and horizon. Along Lihimaliao stream at a point about f mile E. of 

 Xjenja, Tanganyika ; Upper Oxfordian(P). 



Remarks. The type-specimens of this species came from the locality " 1-5 km. 

 W. of the Mahokondo stream, 24-5 km. N.W. of Kiswere ", where the beds are now 

 known to be Callovian in age. The single ill-preserved fragment of a Nerinella now 

 recorded appears to belong to N. maelleri, but it does not allow Muller's published 

 description, referred to below in the description of N. cutleri, to be amplified. 



Nerinella cutleri sp. nov. 

 PI. 30, figs. 4«, b 



1914. Nerinella Credneri (Muller) ; Dietrich : 142, pi. 12, fig. 8 (non Nerinea credneri Muller 

 1900 (non Zittel), = Nerinella muelleri Cox). 



Specific name. After the late W. E. Cutler, the first leader of the British Museum 

 East African Expedition. 



Diagnosis. Shell very slender, up to about 13 cm. in length ; whorls feebly 

 concave to almost flat, their height approximately equal to their diameter ; earlier 

 whorls ornamented with very obscurely granose spiral threads, the number of which 

 increases to about nine at a diameter of about 5 mm. ; later whorls almost smooth. 

 One prominent fold low on the columella ; one prominent parietal fold occupying 

 the angle between the columella and the upper wall of the whorl ; one broad-based 

 fold, which usually is more or less quadrate in cross-section with two well-marked 

 inner angles, but is not definitely bifid, just below the middle of the outer wall ; and 

 (in some specimens only) a very weak fold on the basal wall. 



Holotype and paratypes. Holotype, no. G. 46026, a broken specimen selected 

 because it retains its surface ornament. Numerous paratypes, the majority eroded. 



Localities and horizon. Several localities in Tendaguru neighbourhood (Ki- 

 pande path (type-locality), N. of Kipande, 1 mile N.W. of Tendaguru hill, scarp at 

 Kindope, Namapuya creek) and Kinjele, 5 miles W. of Mtapaia, N. of Tendaguru ; 

 Upper Kimmeridgian, Nerinella Bed. Lilomba creek and f mile S. of Nautope, near 

 Tendaguru ; Upper Kimmeridgian, " Trigonia smeei " Bed. Hillside 3 miles E. of 

 Rahmu, south of the road to Mandera, N.E. Kenya ; Upper Oxfordian, Seir Lime- 

 stones. 



Remarks. The common Tendaguru Nerinella has hitherto been identified as N. 

 credneri (Muller), a species more correctly known as N. muelleri Cox and recorded 

 above. This latter species has been accepted as a long-ranging one both by Dietrich 

 (1914 : 142) and by Hennig (1924 : 51), but this conclusion seems to need critical re- 

 examination. For interpretation of N. muelleri I have to rely mainly on Muller's 

 description and figures. Externally, this species is very close to the Tendaguru 

 form both as regards whorl outline and ornament, the nodose threads which are 

 present on the earlier whorls disappearing at a later growth-stage, leaving the surface 



