174 Annals of the South African Museum. 



to bear a very close resemblance to this specimen, but it is described 

 as having only 50-60 ribs on the surface. 



On the nodule in the Geological Society's Museum holding the 

 iDrachial valve, there is a pedicle valve almost in contact and of the 

 same relative size, and therefore probably belonging to the same 

 species and individual. It is gently convex, and has a small beak 

 rising a little above the hinge-line ; there is an elongated hinge-area, 

 a pair of large diductors, and a faint median septum. The surface 

 is coarsely punctate near the margin, as in Gh. of. coronatus, and 

 the cardinal line is furnished with a few slender spines. 



As Ulrich has remarked, the pustulate surface of the casts is 

 noticeable in several species of Chonetes, such as Ch. bretzi Schnur," 

 and was referred to by Kayser. f 



Dimensions. — Length (No. 129) 20 mm. ; width (No. 129) 32 mm. 



Locality. — (No. 129) " Locality unknown." 



CHONETES atf. SETIGER Hall. 

 (Plate XXL, figs. 1, 5.) 



There is a small group of about half a dozen examples of a species 

 of Chonetes on a rock-specimen (No. 126) from Witzenberg Valley, 

 Ceres. The shell of this form is small, semi-elliptical, not quite as 

 long as wide ; the hinge-line is straight, and equal to the widest part 

 of the shell ; the cardinal angles are rather less than right angles. 

 The pedicle valve is gently convex, but flattened towards the cardinal 

 angles; the beak is small and pointed, scarcely rising above the hinge- 

 line, which bears 3-4 spines on each side. There is a weak median 

 depression down the centre. The teeth are small, and there is a 

 low median septum extending nearly half the length of the valve. 

 The surface is marked by straight radiating rather strong subangular 

 ribs increasing by bifurcation and intercalation near the margin to 

 about 35-40, and crossed by fine concentric striae. In the weak 

 median depression there are four ribs. The brachial valve is 

 flattened to slightly concave ; the beak is very small and incon- 

 spicuous, and there are 2-3 concentric wrinklings near the lateral 

 angles. 



Dimensions. — Length 8 mm. ; width 10 mm. 



Affinities. — The species which seem most closely allied to this form 



* Schnur, Palseontographica. iii., 1854, p. 243, t. xlv., fig. 7 d. 

 t Kayser, Zeitschr. dent. Geol. Gesell., xxiii , 1S71, p. G3G. 



