ART. 16 



FOSSIL REPTILES FROM MONTANA GILMORE 



25 



Measurements ^^ 



Greatest length in a straight line 570 



Greatest width of proximal end 275 



Greatest width of distal end 23 



Dermal armor. — Inter- 

 mingled with the scattered 

 parts of the skeleton some 

 fifty dermal bones of this 

 one individual were col- 

 lected. These present a 

 variety of kinds, spines, 

 large and small; coossified 

 plates ; rounded scutes, 

 with and without keels; 

 and numerous granular os- 

 sifications. Although this 

 specimen will contribute 

 but little to our knowledge 

 of the arrangement of the 

 dermal armor, it does give 

 a considerable insight into 

 the character of the os- 

 seous dermal covering. 



Comparison of ^these 

 scattered plates and spines 

 with those of Palaeoscincm 

 in the American Museum 

 of Natural History, New 

 York, where the armor has 

 been preserved in situ en- 

 ables me to recognize the 

 proper location of many 

 of these scattered bones. 

 Furthermore the close sim- 

 ilarity in shape, size, and 

 association makes it at once 

 apparent that we are deal- 

 ing here with two animals 

 that are generically alike. 



Neck plates. — The der- 

 mal armature covering the 

 neck is represented by 



three plates each composed of either two or three coossified bony 

 scutes. These are illustrated in Plate 5. The smallest of these 

 plates, a complex of three scutes (fig. 3, pi. 5) is tentatively regarded 



Figure 17. — Left ischium of Palaeoscincus rugosi- 

 DENS. Type. No. 11868, U.S.N. M. Lateral view. 

 II. J Articulating surface for ilium ; P., Articu- 

 lating SURFACE FOR THE PUBIS. ABOUT ONE-FOURTH 



natural size 



