110 Morgan Expeditions. 



XIII. — Morgan Expeditions, 1870-71 : On the Devonian 



Trilobites and Mollusks of Erere, Province 



of Parti, Brazil. 



Bv CH. FRED. HARTT, 

 Prof, of Geology in Cornell University, 



AND 



RICHARD RATHBUN, 



Assistant in the Museum of the Boston Society of Natural History. 

 Read March 9, 1S75. 



We have given in this paper descriptions of the trilobites 

 and of all the species of mollusks, not including the braehio- 

 pods, collected by the parties of the Morgan Expeditions, in 

 1870 and '71, from the Devonian rocks of the plain around 

 the little village of Erere. In the Bulletin of the Buffalo 

 Society of Natural Science, for January, 1874, Vol. I, No. 

 4, Prof. Hartt has described at length the geography and 

 geology of the Erere-Monte-Alegre district, in which occur 

 the fossiliferous Devonian beds forming the plain of Erere. 

 These beds consist of thin horizontal layers of white and 

 reddish sandstones, interstratified more or less with shales. 

 Both the sandstones and the shales contain at a few points an 

 abundance of fossils, closely related to, and in some cases 

 identical with, forms characteristic of the middle Devonian 

 rocks of North America. The brachiopods, the most abund- 

 ant fossils in the Erere Devonian, were described by Mr. 

 Rathbun in the work above cited, in a paper immediately 

 following that of Prof. Hartt. There then remained for de- 

 scription the mollusks, including six forms of gasteropods 

 and eight of lamellibranchs, with a single form of Tentacu- 

 lites, two forms of trilobites of the genera Dalmania and 

 Homalonotus, both probably new, and a number of obscure 

 forms, many of which are entirely unrecognizable. 



The mollusks and trilobites in the Devonian at Erere are 

 confined entirely to the sandstone, no traces of either having 



