262 Annals of the South African Museum. 



rounded ; posterior end broad, a little produced near the back, and 

 diagonally truncated with a small sinus near the ventral margin ; a 

 slight depression extending from the umbo to the middle of the 

 ventral margin ; valves with fine concentric lines and a few unequal 

 concentric wrinkles. Length 1|- inches ; breadth 2 inches." 



In addition we may remark that in the internal cast of one in- 

 dividual (No. 89) with both valves in apposition, there are about 

 16 small obliquely transverse teeth visible on the hinge-line behind 

 the beaks ; between the beaks there are about 10 smaller transverse 

 teeth arranged in a fan-like manner, and in front of the beaks there 

 are 5-6 stouter transverse teeth sloping forwards. Our specimens 

 consist of internal casts of both valves and impressions of the exterior 

 of the shell. One (No. 89, internal cast), measures 44 mm. in 

 length and 31 mm. in height. Three occur in pinkish-brown 

 argillaceous nodules, and one in a tough, dark, fine grained, sandy 

 rock. 



Affinities. — P. orbiyityi, Clarke," from the Devonian of Brazil, is 

 an allied species. 



Localities.— {Nos. 84, 88, 89) Ezel Fontein, Ceres ; (No. 100) Stink 

 Fontein, near Triangle (between 1st and 2nd Sandstones) ; Hot- 

 tentot's Kloof (type). 



PAL.EONEILO SUBANTIQUA, sp. nov. 

 (PL XXXII., figs. 4, 4a.) 



A nearly perfect cast of both valves in apposition (No. 85) and the 

 impressions of the exterior of both valves of the same shell (Nos. 86, 

 87), are contained in a pinkish-brown soft argillaceous nodule. The 

 features, though showing points of resemblance to P. antiqua 

 (Sharpe), and P. rudis (Sharpe), are yet sufficiently distinct to 

 warrant us putting it into a new species, as a close examination of 

 Sharpe's type specimens confirms. 



Description. — Shell elongate - elliptical, rather produced pos- 

 teriorly, not quite twice as long as high ; basal margin very 

 slightly curved ; anterior end broadly rounded ; posterior end 

 rather narrower, more pointed, subtruncate below, slightly excavated 

 by weak sinus in inferior margin ; cardinal line nearly straight. 

 Valves moderately convex, most so near beaks, flattened and 

 compressed posteriorly ; beaks situated at about one-fourth the 



* Clarke, op. rit., p. 74, pi. viii., tigs. 14-17; Katzer, op. cit., p. -JO-^, t. xiii.., 

 fi". l'.». 



