AMAZONIAN UPPER CARBONIFEROUS FAUNA. 495 



agree in these respects with authentic specimens from Nebraska 

 City. 



Aviculopecten sp. — A large coarsely ribbed left valve and a 

 smooth right valve, ribbed on the posterior ear, are presumed to 

 belong together. A Kentucky shell described by Cox under the 

 name of A. providence sis agrees in size and some other characters 

 but no close comparison can be made. 



Aviculopecten (Streblopteria) hertzeri. — The Brazilian specimens 

 agree very well with the figures and description of the Ohio shells. 



Avicula, five sp. — The general character of the aviculoid forms 

 of the fauna is indicated by the comparisons of the above table. 

 All were regarded as new, though on direct comparison of authen- 

 tic specimens the first, and possibly the second, may prove iden- 

 tical with A. longd, from which, however, it appears to differ in its 

 larger size, less attenuated form, shallower sinus and smaller ear. 

 The three last species have the general appearance of Bakewellia 

 but the hinge characters are those of Avicula. 



Pseudomonotis sp. — Apparently identical with specimens from 

 Nebraska City, referred with doubt by Meek to P. radialis, Phil- 

 lips, but thought to be really distinct. 



Posidonomya (?). — A peculiar type with the surface ornament- 

 ation of Posidonomya and the form of Avicula. Avicula acosta, 

 Cox, from Kentucky, is perhaps congeneric, but differs in the 

 character of the ears. 



Pinna peracuta. — Fragments from the Curua indicate a length 

 of about 20 centimeters. The material is too fragmentary for 

 satisfactory comparisons, but appears to be identical with frag- 

 ments from Kansas, referred to Shumard's species. 



Myalina kansasensis. — Compared with Kansas specimens the 

 Brazilian form seems never to have attained so great a thickness 

 in the cardinal region, but otherwise they present no differences 

 of consequence. Small specimens with a well developed lobe 

 have the aspect of M. szvallowi, McChesney, but are connected 

 by insensible gradations with the larger more typical forms. 



