50 Annals of the South African Museum. 



T. heterosculpta differs, however, from its African allies by the less 

 posterior elongation of the shell. 



Here again, in the Belgrano beds, we find an associated Gervillia 

 of large dimensions, which does not appear to be widely removed 

 from G. dentata Krauss, while a large Astarte (A. perlata Stanton) 

 with short and deeply excavated lunule, may be said to have its 

 parallel in the Ooniia beds of Cutch, if we confine the comparison 

 to broad outward features. At a somewhat lower horizon in the 

 Pueyrrydon Series (the Gio beds) Ostrea tardensis Stanton, which 

 occurs abundantly, represents a type of Ostrea or Exogyra which 

 has much in common with Exogyra imbricata Krauss ; and to judge 

 from the description of 0. tardensis, it seems likely that these two 

 forms may really be very closely comparable. A special value can- 

 not, of course, be attached to the comparison of such types as these 

 if studied alone, but the resemblance gains significance when viewed 

 in connection with the other Mollusca above discussed. It will be 

 seen therefore, that although the basis of comparison is somewhat 

 slender, yet the occurrences above noted in no slight measure 

 suggest the closest alliance with the niolluscan fauna of the South 

 African Neocomian ; and it may be added that there is nothing in 

 the Pueyrrydon fauna itself to contradict the assumption that we 

 are dealing with a western part-equivalent of the Uitenhage 

 development. 



A search for further traces of the characterising elements of the 

 Uitenhage fauna in the Lower Cretaceous deposits of South America 

 reveals evidences of a very suggestive description. The Lower 

 Cretaceous beds in Bolivia and Chili which have yielded Trigonia 

 transitoria Steinmann * are probably of similar age and seem to 

 represent the more northerly equivalents or part-equivalents of the 

 Pueyrrydon Series. Trigonia transitoria has also been found to 

 occur abundantly at the Arroyo Triuguico and at Quili Malal in 

 the Argentine Republic, in strata ascribed by Behrendsen 1 to the 

 Neocomian. It occurs, moreover, with significant associates in the 

 Trigonia-beds of Lower Neocomian age exposed on the left bank 

 of the Rio Agrio, opposite to Las Lajas (Argentine Republic) ; J 

 these beds yield another member of the Pseudo-quadratse (T. 

 neuquensis Burckhardt) and a Trigonia very closely resembling the 

 South African T. conocardiiformis, as well as an Eriphyla in some 

 respects comparable w r ith the South African Astarte (Eryphyla) 



* Steinmann (1), p. 260; Steinmann (3); R. A. Philippi (1), p. 63 ; Paulcke (1), 

 p. 297. t Behrendsen (1), p. 25. 



| Burckhardt (1), p. 21. Burckhardt (2), pp. 72-75, 111, 112. 



