iSgS.j IP'orljiuin, Extinct Cainelidte oj North America. I 23 



of premolars in both* jaws, the loss of the first and second pairs 

 of incisors in the upper jaw in the adult stage, and the at least 

 ])artial coossification of the metapodials of both fore and hind 

 feet into cannon bones. 



Procamelus robustus Leidy. 



I place as synonyms of the above those proposed by Cope, 

 Protolabis Jicferodoiitiis and Protolabis prcheiisilis. The type 

 specimen, as figured by Leidy, consists of a lower jaw bearing all 

 the premolars and molars with the exception of the second, 

 together with the second and third molars of the upper jaw. The 

 jaw is broken just in advance of the first premolar so as not to 

 show the characters of the incisors, canine and chin. In Cope's 

 type of P . heterodontus the lower jaw is preserved as far l)ack as 

 the root of the last premolar, and this is associated with the 

 almost complete superior dentition. 'I'he type of P . prehensilis is 

 represented by the front of both rami of the lower jaw, associated 

 with a last lower molar. A careful comparison of these speci- 

 mens reveals a remarkable agreement in all details, and I do not 

 think there can be any question of their belonging to one and the 

 same species. The only difference worthy of note is seen in the 

 jaw fragment which constitutes the type of P. prehensilis ; in this 

 specimen the chin is not so abrupt nor deep, and the lower border 

 of the symphysis is more nearly in line with the long axis of the 

 jaw. The size is practically the same in all. I distinguish the 

 species by tlie following characters : Size, large ; lower molars 

 with much greater transverse diameter than in other species ; 

 symphysis not coossified ; chin abrupt and deep. In one speci- 

 men only is the upper incisor dentition known, and in this the 

 first and second incisors are retained. It may transpire that this 

 is not an abnormal case as expressed above, but that it is a further 

 character of the species. No other parts of the skeleton are 

 known with certainty. 



Procamelus occidentalis Leidy. 



This species is by far the most abundant of the Camels in the 

 Loup Fork IJeds. 1 regard the name proposed by Leidy, Homo- 



