1874.] 241 IRathtran. 



This conclusion, it will be noticed, is strictly in accordance with the 

 general tendency of zoological opinions at the present time and al- 

 most identical with the results taught by Herbert Spencer in his 

 works on biology, although I was not aware of this until after they 

 were written. Many of the facts supporting the positions assumed 

 have already been published in various scattered papers, but these 

 will be united and accompanied by others since discovered in the 

 partially completed memoir of which this is an abstract. 



Preliminary Report on the Cretaceous Lamellibranchs 



COLLECTED IN THE VICINITY OF PeRNAMBUCO, BRAZIL, ON 



the Morgan Expedition of 1870, Ch. Fred. Hartt in 

 charge. By Richard Rathbun, Assistant in the Museum 

 of the Boston Soc. of Nat. History. 



After partially completing his explorations on the lower Ama- 

 zonas during the Morgan Expedition of 18 70, 1 Prof. Hartt directed 

 two members of his party, Messrs. O. A. Derby and D. B. Wilmot, to 

 explore various portions of the coast, between the mouth of the Ama- 

 zonas and the city of Pernambuco. In the neighborhood of the lat- 

 ter place were found several outcrops of fossiliferous rocks, which 

 have since proved to be of cretaceous age. Quite extensive collec- 

 tions of the contained fossils were made and sent to this country, and 

 last year the mollusca were offered me for study. 



The localities from which the specimens were obtained are three 

 exposures, situated at and near the mouth of the Rio Maria Farinha, 

 and all included within a radius of two or three miles. The Rio 

 Maria Farinha is but a small stream, which, in the latter part of its 

 course, flows nearly due east, and enters the ocean at a point about 

 eighteen miles north of Pernambuco, and a few miles south of the 

 island of Itamaraca, lying just off the coast. On the north side of the 

 river, at its mouth, is an elevated point called Nova Cruz, which rises 

 in a cliff about twenty-five feet in height and is composed mostly of 

 beds of colored clays. In the upper part of this cliff appears a single 

 layer, about three feet in thickness, of a grayish, fossiliferous lime- 

 stone, with clay immediately above and below it. The entire cliff is 



*For a brief account of this Expedition, see "Preliminary Report of the Mor- 

 gan Expeditions, 1870-71," by Ch. Fred. Hartt. Bulletin of the Cornell University, 

 (Science), Vol. I, No. 1, 1874. 



PROCEEDINGS B. S. N. H. — VOL. XVII. 16 FEBRUARY, 1875. 



