210 



BRITISH FOSSIL TRIGONI^. 



Trigonia conocardiiformis, Krauss. 



Of this remarkable species, so abundant in certain districts in Southern Africa, the 

 single imperfect example in the British Museum is herewith figured. I have deemed 

 it expedient to give the subjoined figures partly to correct an error induced by the 

 reduced and inadequate figures given by Krauss, which appeared to me to represent 

 one of the Clavellata ; the Museum specimen undoubtedly associates it with the 

 crenulated examples of the Scadra (see pp. 120, 121). 



The general figure is unusually lengthened ; the numerous curved, slightly crenulated 

 costse, widely separated anteally, are much smaller and more closely arranged posteally ; 

 they all disappear upon the upper surface of the valve; the spaces representing the area 

 and escutcheon are separated and apparently plain. The specimen, which is the only 

 one known to me, is imperfect posteally, and would be slightly more lengthened when 

 entire. The interior exhibits the hinge-processes and sulcations of the left valve, massive 

 and spreading, but partially destroyed. 



This gigantic species is not without a certain resemblance, both in the general figure 

 and arrangement of the costae, to the Belgian T. EUsob of the Whetstones of Bracquegnies, 

 but the larger anteal costse are without the rounded papillary prominences of that 

 species. The smaller posteal costse are nearly straight and directed retrally, as in the 

 smaller Belgian form. 



Trigonia conocardiiformis, Krauss. South Africa. 



