16 



The Ottawa Naturalist [April 



consisting of the "hinder portion of the cranium of a small indi- 

 vidual wfth part of the horn-cores," from the Pleistocene of the 

 Upper Porcupine River, Yukon. 



In the "Smithsonian Miscellaneous Collections," Vol. iii, pt. 

 2, 1905, is a paper on "Scaphoceros* tyrrelli, an extinct ruminant 

 from the Klondike gravels," by Wilfred H.Osgood. This paper is 

 descriptive of the skull of an animal considered by Mr. Osgood 

 to be "evidently related to the existing genus Ovibos, but suffi- 

 ciently different to rank as a separate genus." The type skull 

 is from Bonanza Creek. The remains of musk-oxen in the Yukon 

 mentioned by Mr. McConnell in his report are the specimens on 

 which this new genus has been estabhshed. Mr. Osgood in his 

 important and interesting paper also reviews the literature of 

 Pleistocene species of Ovibos. He assigns 0. cavifrons (Leidy) 

 to Scaphoceros, and retains the genus Bootherium with bonibi- 

 frons as the type. In the skull of Scaphoceros tyrrelli from Bon- 

 anza Creek the teeth are preserved, an important feature, as no 

 teeth have been found with the Pleistocene remains generally 

 hitherto referred to the genus Ovibos under different specific 

 names in Canada and the United States. 



The tooth from Rock Creek, B.C., is in diameter about three- 

 fifths the size of the last upper molar of 5. tyrrelli, and its pro- 

 portions are quite different. As already mentioned, it is nearly 

 iDut not quite the size of the posterior molar of an adult male of 

 Ovibos moschatus in the Museum of the Geological Survey, and 

 in most particulars agrees very closely with it. As the styles or 

 costae are more slender, is is for the present only provisionally 

 referred to the living form. In comparison with the correspond- 

 ing tooth of an adult specimen of Ovis montana Cuv., the Moun- 

 tain sheep or Big-horn, there are general resemblances. It is in 

 size between the tooth of the mountain sheep and the musk-ox, 

 but more nearly approaches the latter. 



Figures in the accompanying plate are given of the tooth 

 from Rock Creek. In comparing it with the corresponding tooth 

 of the adult male musk-ox from Fort Rae, the three costae or 

 styles of its outer surface are seen to be more slender, but the 

 proportionate development of the intermediate costae or longi- 

 tudinal ribs is about the same, and the tooth pattern is almost 

 identical. The Rock Creek specimen is moderately worn and the 

 posterior cement lake (valley) in the grinding surface connects 

 at its anterior end with the longitudinal depression between the 

 lobes on the inner side of the tooth. The complete enclosure of 



*The generic term Symbos has since been substituted by Mr. Osgood 

 for Scaphoceros (preoccupied). Vide, Proceedings Biological Society of 

 Washington, Vol xviii, p. 223. Oct. 17, 1905. 



