496 THE JOURNAL OF GEOLOGY. 



Myalina sp. — Similar to M. subquadrata, Shumard, but proba- 

 bly distinct. 



Modiola, two sp. — The two forms differ materially in aspect, but 

 the differences are due to the character of the material in which 

 they are preserved. That from the shale of Pacoval is similar in 

 many respects to M.(?) subelliptica, Meek, from Nebraska, but 

 the latter is narrower with a less inclined hinge line. The Itai- 

 tuba specimens are more gibbous than any known to me from 

 elsewhere. 



Yoldia sp. — Too badly preserved for identification, but very 

 similar to Y. subscitula, Meek & Hayden. 



Nuculana sp. — Similar to N. obesa, White, but too imperfect for 

 a satisfactory comparison. 



Macrodon,two sp . — The smaller is identical with specimens from 

 Leavenworth, Kansas, labeled M. carbo?iarius by Mr. Meek, but 

 considered by Dr. White to be M. temdlineatus. The larger one 

 resembles somewhat M. carbonaritis, Cox, but has coarser ribs 

 and is apparently distinct from any described North American 

 species. 



Sole?iomva sp. — A single specimen occurs in chert from Bar- 

 reirinha on the Tapajos above Itaituba, where it is associated 

 with Productus cora. It resembles somewhat some figures of 5. 

 biammica, de Verneuil, but differs from the generality of figures 

 of that species and is probably distinct. 



Solenopsis sp. — Referred to this genus from a general resem- 

 blance to ^". solenoides, Geinitz, from which it is distinguished by 

 being wider posteriorly than anteriorly. 



Schisodus,foursp. — No. I is referred with doubt, due principally 

 to imperfection of the material, to 5. wheeleri; No. 2 is appar- 

 ently identical with the Nebraska shell referred by Mr. Meek 

 with doubt to 5. roscus but thought by him to be really distinct ; 

 No. 3 is of the type of 6". wheeleri, but is different from any 

 North American shell with which it has been compared ; and 

 No. 4 is possibly a dwarf variety of No. 3, but is regarded as 

 more probably distinct. 



