494 THE JOURNAL OF GEOLOGY. 



Prodnctus nebrascensis. — A specimen from the limestone at the 

 base of the Serra de Tajauri, is almost certainly identical with the 

 North American shell ; those from other localities are too imper- 

 fect for positive identification. 



Productus punctatus (?). — A specimen from Pedra do Barco, is 

 identical with the North American shells usually referred to P. 

 punctatus but which have been separated by Dr. White under the 

 name of P. ?ievadensis. 



Discina. — Two or more species probably occur. One of these 

 is very similar to D. missouriensis, Shumard. 



Entolium aviculatum (?). — The doubt in regard to this species 

 is due to imperfection of the material. So far as the characters 

 can be made out the agreement with the North American type is 

 complete. 



Lima retifera. — In a direct comparison with Nebraska City 

 specimens no difference of importance could be detected, as these 

 show a grouping of the ribs in pairs very characteristic of the Bra- 

 zilian shells but not represented on most figures of this species. 



Aviadopecten occidentalis. — The material here referred shows 

 considerable variability, but no constant characters could be 

 found for distinguishing more than one species, or for separating 

 this from the North American form which appears to be equally 

 variable. The more typical forms with subequal ribs and furrows 

 are from Itaituba, while those from the Curua have furrows wider 

 than the ribs, giving these an alternating appearance. 



Avicidopecten carboniferous .■ — So far as can be made out from 

 a comparison of left valves alone the Brazilian specimens agree 

 perfectly with those from Nebraska City. 



Aviadopecten neglectus. — The hinge line shows obscurely a row 

 of cartilage pits such as are represented by Meek & Worthen 

 on specimens from Illinois. 



Aviadopecten coxanus. — Compared with figures of this species 

 the Brazilian shells appeared to differ in the greater length of the 

 posterior sinus and by the shortness of the hinge line but they 



