258 



The length of the series of lower molars and premolars together, in the 

 different species, is as follows: 



Lines. 



Length of the series in the llama 32 



Length of the series in the camel GO 



Length of the series in the Auchenia hesterna 84 



Accompanying the inferior molar specimens from California there is a 

 specimen of an upper molar represented in Fig. 3, Plate XXXVII, which, 

 from its constitution and size, is supposed to belong to the same species, if 

 not the same individual. 



It is a first or second true molar of the left side, and closely resembles the 

 corresponding teeth of the llama. 



Its comparative measurements are as follows : 



Second upper molar. 



Breadth of the triturating surface. 

 Width of the triturating surface . 



Width of crown near base 



Length of crown 



Llama. 



Camel. 



Lines. 



Lines. 



9f 



20 



8 , 



11 



8 



13 



n 



10 



Auchenia 

 hesterna. 



Lines. 



23J 

 12 



29 



Palauchenia 

 magna.* 



Lines. 



21 



Hi 



16J 



' Professor Owen's measurements given as those of the second lower molar. 



PROCAMELUS. 



The genus Procamelus, or Protocamelus, was originally named from remains 

 discovered by Professor Hayden, in the Tertiary sands of the Niobrara River, 

 Nebraska. Three species were indicated from the locality under the names 

 of Procamelus robustus, P. occidentalism and P. gracilis. The specimens show 

 that Procamelus possessed a series of four premolars and three molars to the 

 lower jaw, from which we may infer an equal number to the upper jaw. The 

 molars and last premolar have the same form as those of the camel. 



Among the Texan collection of fossils, loaned by Professor Buckley, there 

 is a specimen of a tooth supposed to belong to Procamelus. It is Repre- 

 sented in Fig. 21, Plate XX, and was found in association with the equine 

 teeth before described, and represented in Figs. 14, 15, and 17 of the same 

 plate. It is a first or second upper molar, and sufficiently resembles the 

 corresponding tooth of P. occidentalism as we may suppose it would appear in 



