R. F. Osborn — Mammalia hi* North America. 379 



The frontal margin is marked by a convex fold of the test. 

 The axis is annulated. The anterior six annulations apparently 

 belong to the cephalon, the sixth one being considerably 

 stronger than the others and probably representing the occip- 

 ital ring. The pygidial portion is defined by a narrow shallow 

 transverse furrow ; and the axis has two annulations. 



Near the lateral anterior margins are two slight 

 elevations which may represent the palpebral 

 lobes of the eyes, and from them extend two 

 furrows curving inward to the axis and dividing 

 the cephalic region into two portions. The occip- 

 ital pleura are indicated by slight depressions 

 extending from the occipital ring. 



The specimen illustrated in figure 1 has a Figure i.—Tri 

 length of -63 mm and a width of 46 



•mm 



arthrus Beck # 

 dorsal view of 

 larva, x 30. 



Nearly all the specimens with appendages are 

 complete, and lie with the ventral side upward. A few iso- 

 lated fragments only have been observed. Individuals of all 

 ages occur, the majority being aboat half grown. 



So far as noticed, the other species of fossils, which are 

 found strictly in the same association, are young individuals of 

 Tr (nucleus concentricus, Schizomania filosa, Leptobolus insig- 

 ?iis, and Orthis (Dalmanella) testudinaria, ostracoda and 

 graptolites of several kinds, indicating that the deposit belongs 

 to the Utica slate. 



Tale Museum, Xew Haven, Conn., Oct. 9th, 1893. 



Art. LIU. — The Rise of the Mammalia in North America '* 

 by Henry Fairfield Osborn, Columbia College, New 

 York. 



[Vice-Presidential address before the American Association for the Advancement 

 of Science, Section of Zoology, Madison, Wise, August 17th, 1893.] 



Twexty years ago an era opened in the mammalian pale- 

 ontology of Europe and America. Partly inspired by the 

 Odontographie of Riitimeyer, Kowalevsky completed and pub- 

 lished in 1873 his four remarkable memoirs upon the hoofed 

 mammals. He wrote these four hundred and fifty quarto 

 pages in three languages not his own, in French upon Anchi- 

 therium and the ancestry of the horses, in English upon the 



* Some passages in this address have been omitted as indicated by dotted lines. 

 The address will be printed in 'full in the Biological Studies of Columbia College, 

 Part I. 



