232 



It has the characteristic Rodent astragalus, very like that of the earlier 

 Sciuromorphs. The incisor is intermediate between the short -rooted 

 spatulate incisor of the Rodentia. The root is long, but does not grow 

 from a persistent pulp, and the crown is long and pointed, but still 

 retains much of the spatulate shape. The canine and anterior pre- 

 molars are disappearing, the fourth premolar becoming molariform, and 

 the molars showing some traces of an impending change to a type like 

 that of the Wasatch rodents. 



More complete material of many species shows that all the pla- 

 cental mammals were remarkably similar in skeleton structure. They 

 were plantigrade, pentad actyl, with claws or narrow hoofs, short clumsy 

 limbs and long heavy tail. Contrary to expectation the podium and 

 metap odium are not usually arranged in serial order. The carpus is 

 alternating in the four species in which it is known, and the tarsus is 

 serial in only two out of eleven species. Of these two, one is a pri- 

 mate, the other is the ancestor of Phenacodus and has an altern- 

 ating carpus. The direct ancestors of the Perissodactyls and Artio- 

 dactyls do not seem to be among the known Basal Eocene species. 

 The Creodont Claenodon resembles the modern bears in foot structure 

 as well as in the teeth, and may have been ancestral to them. Con- 

 sidering that such widely different types as the Edentates, Rodents, 

 Primates, and Amblypods have been traced to their first beginnings in 

 the Basal Eocene, it may be concluded that the first differentiation 

 of all the Placental mammals took place at the beginning of the Ter- 

 tiary, and not in the Cretaceous as has frequently been stated. 



Dr. Matthew's paper was discussed at length by Professor Osborn 

 and Dr. Wortman. 



Mr. Harrington reported on some observations which he had made 

 on "Earth Worms during Copulation". He described an organ which 

 apparently has been usually overlooked. This organ, the spermatophore 

 of some authors, consists of a modified seta, much enlarged at the ex- 

 tremity and functioning, as Mr, Harrington suggests, to force sperma- 

 tozoa into the seminal receptacles of the other worm. 



Gary N. Catkins, 

 Seer, of Section. 



Abgeschlossen am 19. December 1897. 



Krommaansche Buchdruckerei (Hermann Pohle) in Jena. 



