268 Annals of the South African Museum. 



MODIOMOEPHA cf. PIMENTANA, Hartt and Eathbun. 

 (PI. XXXIL, fig. 10.) 



There is one right valve of a shell which probably l)elongs to the- 

 species of Modiomorpha named jnmentana- by Hartt and Eathbun, -•- 

 and found in the Devonian of Brazil. The valve is associated with 

 specimens of Spirifer sp. a (No. 146) from Gamka Poort, and is of 

 an elongate, oblong shape, about twdce as long as high, slightly 

 increasing in width posteriorly ; the basal and cardinal margins are 

 nearly parallel ; the hinge-line is straight and about three-fourths- 

 the length of the shell, the posterior end being produced behind it 

 and obhquely truncated above ; the anterior end is short, subtruncate 

 and rounded ; the beak is subanterior, broad, obtuse, not prominent, 

 incurved and scarcely rising above the hinge-line. The surface of 

 the shell is rather strongly convex; a broad undefined umbonal 

 ridge runs obliquely across it to the posterior ventral margin ; the 

 post-cardinal slope is somewhat flattened, and a faint depression is 

 traceable in front of the uml)onal ridge running from the umbo to 

 the ventral margin. The ornamentation, so far as it is preserved, 

 consists of concentric striae with a few stronger wrinkles interspersed. 



Dimensions. — Length 31 mm ; height 15 mm. 



Affinities. — The species M. pimentana is somewhat variable in 

 shape, and our specimen most resembles those figured by Clarke 

 {pp. cit.) on plate vi., figs. 8 and 9. 



Localiti/.—{^o. 146) Gamka Poort. 



MODIOMOEPHA aft". SELLOWI, Clarke. 



(PI. XXXII., fig. 11.) 



There is one small specimen (No. 122) of a right valve of what is 

 proliably a young example of Clarke's species Modiomorpha selloici t 

 from the Devonian of the Eio Maecuru. It differs from the large 

 specimens figured by that author in its rather narrower, more elon- 

 gated and more oblique shape. The posterior limb shows one of the 

 divergent longitudinal ridges mentioned by Clarke, and the muscular 

 scars are well marked. Its surface is depressed, the greatest con- 

 vexity being in the anterior and umbonal regions ; the posterior and 

 lateral portions are almost concave. The posterior margin and 

 hinge-line meet at an obtuse angle ; the hinge-line is straight 



* Hartt and Eathbun, op. cit., p. 123 ; Clarke, op. cit., p. 5'2. pi. vi., figs. 4-9. 

 t Clarke, op. cit., p. 51, pi. vi., figs. 14-lf). 



