152 PROCEEDINGS OF THE PALEONTOLOGICAL SOCIETY 



CONTINUATION OF PALEONTOLOGIC PAPERS 



The first paper in the afternoon session was a study in evolution, which 

 was presented by Doctor OTonnell and was discussed by Professor 

 Osborn. 



ORTHOOENETIC DEVELOPMENT OF THE COST^ IN THE PERISPHINCTIN^ 

 BY MARJORIE O'CONNELL 



(Abstract) 



The various interpretatioUvS which have been given to the term "Ortho- 

 genesis" are discussed and the distinction is drawn between the law and the 

 explanation of orthogenesis. A statement will be made of the data available 

 to the embryologist, zoologist, vertebrate and invertebrate paleontologist for 

 orthogenetic studies, with particular reference to the possibilities for the ob- 

 servation of the facts of ortho-ontogeny and ortho-phylogeny. 



As an illustration of the law of orthogenesis, the development of the costse 

 in a single species of Perisphinctes will be described. The bearing of the 

 ontogenetic development on the phylogeny of Perisphinctes will be given. 



An important contribution to the Mesozoic stratigraphy and paleon- 

 tology of Cuba, illustrated by diagrams and lantern slides, was contained 

 in the following paper presented by the junior author : 



DISCOVERY OF THE OXFORDIAN IN WESTERN CUBA 

 BY BARNUM BROWN AND MARJORIE O'CONNELL 



(Ahstract) 



The senior author, in the course of two trips to western Cuba, made collec- 

 tions from a compact nodular limestone, the Jurassic age of which was first 

 pointed out by De La Torre, who discovered Perisphinctes in some of the 

 nodules. No species have heretofore been described from the Jurassic of 

 Cuba, but the horizon has been considered to be of the same age as the Tdo- 

 ceras beds of Mazapil, in Mexico — that is, Kimmeridgian. However, in work- 

 ing up the fauna, which consists mainly of ammonites, it was found that all 

 of the species are closely related to or identical with forms in the Oxfordian 

 of Durango, Mexico, which has been described by Burckhardt. 



The general stratigraphic relations in Cuba will be discussed and the corre- 

 lation with European and Mexican equivalents will be given, as well as a brief 

 description of the new fauna. 



The following paleontologic paper was then read by title : 



A NEW EURYPTERID HORIZON 

 BY GEORGE HAJLCOTT CHADWICK 



(Al)stract) 



Barge canal excavations near Pittsford, New York, have disclosed a new 

 bed of Eurypterus pittsfordensis included in red Vernon shales, probably forty 



