68 



COMPARATIV^E TABLE OF HORN CORES, &.C., OF SPECIES OF MONOCLONIUS AND 



POLYONAX. 





Monoclonius 

 ciassua. 



Polyonax 

 mortuarius. 



Monoclonius 

 recurvicornis. 



Monoclonius 

 sijlieuoceras. 



Monoclonius 

 dawsoni. 



Monoclonius 

 canadensis. 



Monoclonius 

 belli. 



Nasal 

 horn. 







Robust, 



depressed, 



curved 



forward. 



Long, 



straight 



laterally 



com pressed, 



upright. 



Slender, 

 long, very 

 slightly 

 curved back- 

 ward. 







Orbital 

 horn. 



Very small, 



upright, 

 flattened on. 

 outer side. 



Supposed 



horns long 



and 



slender. 



Robust, 

 short, flat- 

 tened on 

 outer side, 

 upright. 





None 



Moderate size, 

 slender, 

 curved 

 obliquely 

 inward and 

 backward ; 

 base over- 

 hangs orbit. 





Squam- 

 osal. 



Narrow, and 



thin with 

 scalloped bor- 

 der ; coossi- 

 fied with 

 parietals. 









Thin, with 



scalloped 



border ; fewer 



emarginations 



than in M. 



crassus. 



Plate like ; 

 lower poster- 

 ior border 

 slightly 

 scalloped. 





Parietals. 



Thin, 



expanded 



posteriorly 



and anteriorly; 



smooth 



behind. 









Thickened 



posteriorly ; 



with two 



incurved 



hooka on back 



border. 



Known only 

 from the pos- 

 terior right 

 lateral exten- 

 sion partly 

 underly- 

 ing squamosal. 



Reversed T- 



shaped, 

 shaft subcy- 



lindrical, 

 anterior ex- 

 pansion 

 thin, pos- 

 terior ex- 

 pansion bar- 

 like. 



Teeth. 



1 Single 

 fanged. 









1 Single 

 fanged. 



Double 

 fanged. 





Stegoceras. G-en. nor. 

 Stegoceras talidus. Sp. nov. 



Plate XXI, figs. 1-5. 



The two symmetrical, compact bones, represented on plate XXI, were found separately. 

 The lower portions of their sides, as well as their ends, consist of sutural surfaces, indi- 

 cating that other bones were firmly united to them and completely surrounded them. 

 A transverse suture divides each almost equally into an anterior and a posterior half. On 

 the lower surface there is evidence of a line of coalescence in a longitudinal direction and 

 extending from end to end. The upper surface of each specimen is dome shaped. 



