No. 3.] AMERICAN ASSOCIATION. 16& 



world of naturalists by announcing his conviction that the ani- 

 mals were not moUusks, and that they had no relations with shell 

 fish whatever, but were true worms. Radical as was this inno- 

 vation in classification, it received the sanction of several eminent 

 naturalists, both at home and abroad. But before this new view 

 could secure general acceptance, it was necessary that the obscure 

 and almost unknown history of the animal from the egg to the 

 adult should, be fully ascertained. This Prof. Morse has at last 

 accomplished. He has succeeded in raising the brachiopod from 

 the e^s: and has studied its internal and external structure in 

 every stage of growth. So to speak, he has seen it in its infancy 

 and childhood, and dissected every portion of it under the micro- 

 scope, drawing, as he can, with one hand and writing a descrip- 

 tion with the other, while his eye was glued to the instrument. 



Briefly then, the embryo commences life as a little worm of 

 four segments, and after enjoying itself in swimming freely in the 

 water for a while, attaches itself to the sea bottom by its posterior 

 segment, and settles permanently. The middle segment then 

 protrudes on each side of the head segment, and gradually in- 

 closes it, thus producing the dorsal and ventral shell so charac- 

 teristic of the entire class. This unlooked for, simple develop- 

 ment could not have been predicated by any study of the adult 

 animal, but remarkably sustains the homologies insisted upon 

 two years ago by Prof. Morse in his papers upon the subject.. 

 The present communication elicited warm approbation. 



ON SOME EXTINCT TYPES OF HORNED PERISSODACTYLES.. 

 By Prof. Edward D. Cope, of Philadelphia. 



It is well known that the type of Mammalia of the present 

 period, which is preeminently characterised by the presence of 

 osseous horns, is that of the Artyodactyla Riiminantia. At the 

 meeting of the Association of last year, held at Dubuque, I an- 

 nounced that the horned mammals of our Eocene period were 

 most nearly allied to the Proboscidians. I now wish to record 

 the fact, as I believe for the first time, that the Perissodactyles 

 of the intermediate formation of the Miocene embraced several 

 genera and species of horned giants not very unlike the Loxolo- 

 phodon and Uintatherium in their horned armature. 



While exploring in connection with the United States Geo- 

 logical Survey of the Territories, I discovered a deposit of the 



