302 F. E: Co/cper Reed^The.Bo7iliei}eld Beth, S. ^Afdca. 



LAMELLIBEANGHIATA..; 1 

 BuCHfOLA SU13PALMATA, sp. iiov. (PI. XVI, Figs. 1, la, 2.) 



Diagnosis. — Shell subqnailrate or subcircular, nearly equilateral 

 and nearly as high as wide, more or less swollen ; hinge-line 

 straight, shorter than shell, cardinal atigles obtusely rounded. 

 Beaks subcentral, a little nearer anterior than posterior end, 

 opposed, directed slightlj'^ forwards, strongly incurved. Valves 

 more or less inflated, most tso in middle, somewhat compressed 

 near cardinal region on both sides of beaks. Surface marked with 

 11-13 raised, flattened, radiating ribs with sharp edges, elevated 

 abruptly above the narrower intercostal grooves, which are I'ounded. 

 The middle 5-7 ribs are stronger than the others, of subequal 

 height and size, and curved slightly forwards; at the margin of 

 the shell they are 1^-2 times wider than the separating grooves. 

 The anterior 2-3 ribs are smaller, less elevated, and slightly 

 concave on their surface, and are curved more upwards ; the 

 posterior 3-5 are likewise lower and much less conspicuous than 

 the middle ones, and have their surface sometimes rather concave, 

 and they are curved up slightly towards the hinge-line. Fine, 

 inconspicuous, regular, closely set, concentric strite cross the ribs 

 and grooves, and are slightly' arched on the former. (These are not 

 distinctly shown in the figures.) 



Dimensions : 



Average leugtli 5-5-6-0 mm. 



,, height ... ... 5-25-0-0 ,, 



,, thickness ... ... 3"50-4-25 ,, 



Locality. — Zwartberg Pass. 



Remarks. — The genus Buchiola has not been previously recorded 

 from South Africa, and I have not found it mentioned amongst the 

 Devonian fossils from South America, to which the fauna of the 

 Bokkeveld Beds has been shown to bear a close resemblance in 

 composition and species. It is, on the other hand, a characteristic 

 European genus, represented, especially in the Rhenish Devonian, 

 by many species which Betishausen ' has described, and it occurs 

 also in North America, where Hall applied the generic name 

 Giyptocardia to it. The range of the genus extends from the Upper 

 Silurian (Bohemia) to the upper horizons of the Devonian. In the 

 Ehenish provinces it appears to be limited to the Middle and Upper 

 Devonian. 



The aflSnities of our South African form are undoubtedly with 

 £. j)a/))ia/a (Goldfuss) - in the shape, numbei', and distribution of 

 the ribs ; but as regards the subequilateral form of the shell and its 

 inflated character B. ruppacJiensis, Beush.,^ resembles it more closely. 

 B. speciosa (Hall),* from the Genesee Slate, is closely allied to, if 

 not identical with, B. palmata, as Beushausen has observed. 



' Beushausen, Lamell. rhein. Devon: Abh. kiJn. preuss. geol. Landesanst., 

 N.F., xvii (1895), pp. 3'22-33S, pis. xxxiv, xxxv. 



* Ibid., p. 333, pi. xxxiv, tiirs. 3-5. 

 3 Ibid., p. 324, pi. xx.xiv, figs. Sa-f. 



♦ Hall : Pala-ont. N.Y., vol. v, pt. 1 (IS83), pi. Ixx, figs. 6-8. 



