NATURAL SCIENCES OF PHILADELPHIA. 371 



Prof. Cope explained the scope of the paj^er read by him as 

 follows : The types of molar teeth are considered to be four, viz., 

 tlie simple conic or truncate (Haplodont) ; the sides of the crown 

 vertically plicate (Ptychodont) ; the apex of the crown tubercnlate 

 (Bunodont) ; or plicate (Lophodont). The Bunodonts were re- 

 garded as either with opposite or alternate, or few or many 

 tubercles. The Lophodonts were considered in respect to their 

 superior and inferior teeth separately, and are divided into ani- 

 sognathous, having the maxillary teeth developed more exten- 

 sively than the mandibular, and isognathous, where the develop- 

 ment of the molars in the two jaws is identical. With respect to 

 the structure of the upper molars they are found to represent 

 opposite and alternate tubercles, and are hence divided into 

 Antiodont and Amoebodont series. To the former belong the 

 Seleuodont (Ruminant), Tcvpirodont (Tapir), and Trichecodont 

 (Elephant) types ; to the latter, the Falseolheridonf, Symborodont, 

 Bafhjnodonf, and Loxolophodont types. The mandibular teeth are 

 in like manner either antiodont or amrebodont. Of the former 

 kind are Selenodonts, Hyrurodonts (Kiiinoceros), and Tricheco- 

 doiits (Tapir, Elephant, .Manatee, etc.) ; of the latter, Symborodont 

 (Anchitiierinn, PaUeotherium, Palasosyops), Hippodonfii (Equns), 

 and Loxolophodont (Bathmodon, Uobasileus) types belong. The 

 BumincDifia are biserial in the essential constitution of the crests 

 of the upper molars ; the Proboscidians (including Bathmodon and 

 Uobaf<ilens) uniserial, that is, both series of tul)ercles iiniting to 

 form a simple pattern, while the Perissodactyles are intermediate 

 in this respect, with the exception of the true horse, which is 

 Selenodont above. 



The genetic relations of the Lophodont teeth are believed to be 

 to corresponding t^'pes of the Bunodonts, and connecting series 

 from the typical forms of the latter to corresponding genera of the 

 former are shown to exist in most cases, rendering the probability 

 of descent very strong. It results that Bunodonts and Lopho- 

 donts form " homologous groups," and are tlierefore related geneti- 

 cally, as had been pointed out by the writer some years ago. The 

 mandibular dental characters of the Eocene genera Aclisenodon 

 and Ilyopsodus are shown to conform to the antiodont and ama^bo- 

 dont types of the bunodont pattern respectively. 



The types of extremital structure have nearlj' similar relations, 

 but are much further reaching in application, each of the divisions 

 Artiodaciyla, Proboscidia, and Fe7-i.st^odactyla embracing both Bu- 

 nodonts and Lopliodonts. The probable or theoretical ancestral 

 types of Bafhmodon and LJobasileus are suggested, as well as tiiat 

 of the whole of the Mammalia Educabilia, or Gyrencephala, in- 

 cluding man. This is necessarily a pentadactyle plantigrade bu- 

 nodont, probably isognathous, and with cerebral convolutions 

 much reduced. 



