Palceozoic Fossih. 379 



Anterior end imperfect. Cardin.il margin oblique to long axis of 

 shell and dii-ected away from the uml>os at an angle of 140°; 

 hinder portion of the post-nmbonal hinge-line bent slightly down- 

 wards. Inferior margin somewhat curved and directed forwards 

 and upwards. Valves gentlj- and evenly convex ; greatest width 

 behind the umbos and near the upper margin. Ornamentation 

 consistitig of broad concentric rings with finer ridges between ; 

 on one side of the cast the gathering together of the concentric 

 rings at the anterior end is far greater than on the other side, a 

 fact which leads me to think that the Modioiiiorpha form of the 

 shell is produced by distortion. Hinge line edentulous as far aS 

 seen, but the matrix standing u|) between the hinge facets, these 

 being now removed, is broken away in the ])lace where iV. capim- 

 s/.s. Reed, is shown to have a toothed portion of the hinge. Area 

 as in Modiolojisis ( Modiouiorplia) haini, Sharpe, elongately lunu- 

 late. Beaks strongly incurved towards the hinge, sharply pointed. 

 Clavicular buttress small, vertical, concave forwards. 



The position of this internal cast is doubtful. Had it been 

 an external cast it would have been probably referred to the genus 

 yiodioNiorjjJtn, as it would have been also from the edentulous 

 nature of the hinge : the clavicular buttress, however, associates 

 it with forms of Nuculi'ies, such as N'. ahh/rr/afus, Sharpe. The 

 shells of this genus are very variable owing to distortion, one cast 

 in the Albany Museum showing a form i-eferable to N. abhrcvia- 

 tus, and the other side to N. Irrmmeri, Clarke. The very iujper- 

 fect shell figured by Reed as SangidHoJifcs sp^ has much the 

 appearance of this species. 



Dimensions : Height. 3.3 cm. Length, cm. 



Cat. No. 135. Donor : Mr. A. G. Bain, Bokkeveld l)eds, Leo 

 Hoek. This locality, so often given in Bain's pa})er in the trans- 

 actions of the Geological Society, is probably the farm Leeuwen 

 Fontein lying under Hottentot's Kloof, to the west, and adjoining 

 Laaken Vley ; the farm lands lie in a hollow between a ))lunging 

 anticline of Table Mountain Sandstone and the Bokkeveld beds, 

 which rise in terraced escar])ments, opi)osite. 



Ami. 8. A. Mus., Vol. IV., 19U4, p. 252, PI. XXXI., fig. 4. 



