No. 492] SOME AMERICAN CHALICOTHERES 



743 



quite close together, in the Agate Spring Fossil Quarr;^ . As the 

 vertebrae are found to fit one another in a quite perfect manner, 

 there is very little doubt that the cervicals and the dorsals are, 

 excepting the eightli and (^lovciitli dorsals which are evidently lost, 

 correK'tly represented In this speciiiicii. ^Ye found seven cervicals, 

 thirteen dorsals, and tliree antei-ior lunibars belonging to the same 

 individual. The cervical and dorsal regions are apparently 

 quite complete, while three lunibars are lacking, but judging from 

 other individuals found in the quarry the complete number in the 

 lumbar series was six. '{'here was no sacrum with this individual, 

 but we know that tlu^re are four sacral vertebrae. "J'he caudal 

 regi(Mi is not fully known, but 1 judge that it attained a length 

 about e(|uul to that in the rhinoceroses g<Micrally. 



The Cervical Vertebrae.— For an animal with a comparatively 

 small liead, the cervical vert<>bra(> of Moroj)us are (|uite robust. 

 The general structure of thccerNical region .uggeM^ that of the 

 recent horse. With the exce])tion of the gicatcr angularity of the 

 transverse process, the diU'erent position of tln^ arterial canal and 

 the open atlanteal notch, the atlas might be taken for that of a large 

 specimen (,f K,juus rahalhis Tlu- axis i> Mill m<-re s,.uo^..ti,e of 

 the horse, but the inferior keel is larger ainl ihe neural spine 

 higher/ more ..\ erhauiiing in front, and .omeNshat motv robust. 

 ^J^he articulation fnr the atla^ ha^ the ^amc .pout->hape<l (extension 

 anteriorly, but with th(« median protuberance relatively much 

 enlarged, forminu- a cuimous knob which doubtless reproents the 

 primitive odontoid ])r()C(\ss. With the excejxion of the more pro- 

 <luced condition of the centra po^eriorly, the m.,iv bn.adly devel- 

 oped hypapophysial keels inferiorly. the hiuher n(Miral s|)ines, the 

 relatively heavier neural arches, and the larger zygapopln sial faces, 

 thegcneVal make-up of the cenicab bac k of th(> axis in M(u-opus 

 is simi.ar \n that in K(|uns. There i> no v(Mlt>brartrrial canal in 



