170 Annals of the South African Muscmn. 



The characters are the following : — 



Shell transversely semi-elliptical, broader than long, slightly 

 convex in middle, flattened laterally. Hinge-line equal to greatest 

 width of shell. Hinge-area of pedicle valve narrow, triangular, 

 inclined. Brachial valve with large quadrilobate cardinal process 

 and deep dental sockets. Hinge-line finely crenulated. Low, broad , 

 short median septum. Surface ornamented with 100-120 straight, 

 much flattened weak ribs, faint near cardinal angles ; the intervening 

 fine striae are marked by minute pores or tubular openings communi- 

 cating with pustulose elevations on the interior ; the pustules are 

 smaller and more elongated towards the margins. 



Dimensions. — Length -)- 25 mm. (probably about 30 mm., for the 

 anterior margin is imperfect) ; width about 46-50 mm. 



Affinities. — This shell closely resembles Hall's species Strophonella 

 ampla,^' from the Upper Helderberg of North America, particularly 

 in the manner of its pustulation. The form described by Ulrich f as 

 Stropliomcna sp. /3 from the Devonian of Bolivia is possibly identical. 



Locality. — (No. 128) Gydo Pass, Ceres. 



OETHOTHETES SULIVANI (Morris and Sharpe). 

 (Plate XX., fig. 8.) 



1846. Orthis Sulivani, Morris and Sharpe, Quart. Journ. Geol. Soc, 



ii., p. 275, pi. X., fig. 1. 

 1856. Stropho')nena Sullivani, Sharpe, Trans. Geol. Soc, ser. 2, 



vol. vii., p. 209, pi. xxvi., figs. 18, 19. 

 ? 1856. Strophomcna Baimi, Sharpe, ibid., p. 208, pi. xxvi., figs. 13, 



17. 



This species was first described from the Falkland Islands, but 

 subsequently from Cape Colony. The species Strophomena hainii is 

 without much doubt identical. I have carefully examined and com- 

 pared the South African types of both species in the Museum of the 

 Geological Society, and the slight d]fi"erences seem only due to the 

 method and state of preservation of the shells. Sharpe says that 

 in Sir. hainii the ribs increase by insertion, but the specimens show 

 that they also clearly increase by bifurcation exactly as in Orth. 

 sulivani, figured by the same author. In both species the number 



• Hall and Clarke, Palsont. N.Y., vol. viii., pt. 2, 1893, p. 293, pi. xii., figs. 

 13-15. 



t Ulrich, Neues Jahrb. f. Min., Beil. Bd. viii., 1893, p. 70, t. iv., fig. 24. 



