AMAZONIAN UPPER CARBONIFEROUS FAUNA. 493 



undoubtedly represent P. inca, d'Orbigny, prove that the Boliv- 

 ian form does not belong to P. semireticulatus, as usually referred, 

 but rather to the P. costatus group, though probably distinct from 

 the European form. 



Productus cora. — In the argillaceous strata of the Curua and 

 Trombetas the forms here referred become very large and take 

 on extravagant shapes from irregular marginal expansions, but no 

 good characters could be found for separating them from the 

 more symmetrical forms from Itaituba. The material brought 

 from Lake Titicaca by Prof. Alex. Agassiz, though rather unsatis- 

 factory for this type, appears to prove the complete identity of 

 the Brazilian shells with the original Bolivian type of P. cora. 



Productus chandlessi. — A single specimen from Lake Titicaca 

 shows that this form occurs also in Bolivia and thus renders it 

 probable, notwithstanding the differences in the figures, that 

 d'Orbigny's P. peruvianas is identical, in which case that name 

 will of course take precedence. 



Productus batesianus. — The specimens from the localities on 

 the north side of the Amazonas, referred with doubt to this spe- 

 cies, may possibly be distinct. If identical, those from Pacoval 

 and Cujubim represent a dwarf and less distinctly sinuated variety; 

 those from Lake Arapicu agree more nearly with the typical form 

 from Itaituba but are larger. 



Productus rlwmcanus. — North American forms apparently 

 identical with this are referred to P. longispinus, Sow., by Meek 

 & White, from which, however, it seems to me to differ by im- 

 portant internal characters. 



Productus wallacianus. — A small Productus extremely abun- 

 dant in the shale of Pacoval, Rio Curua, is either distinct or a 

 dwarf variety of this species. This type, which appears to be 

 rare or lacking in the North American beds, is represented in the 

 Salt Range by P. opuntia, Waagen. 



Productus clarkeanus. — This is probably identical with P. per- 

 tenuis, Meek. 



