98 THE CERATOPSIA. 



Stegoceras validus Lambe. 1902. 



Type (Nos. 515 a and 1423, Geo!. Surv. Canada) consists of two cranial fragments pertaining certainly to different species 

 and possibly to different genera. 



Original description in Contr. Canadian Pal., vol. 3 (quarto), pt. 2, 1902, pp. 68-69. 

 Lambe, L. M., Contr. Canadian Pal., vol. 3 (quarto), pt. 2, 1902, p. 81. 

 Osborn, H. F., Contr. Canadian Pal., vol. 3 (quarto), pt. 2, 1902, p. 15. 



The present genus and species are based upon the fragmentary remains of three different 

 individuals. Unfortunately Lambe failed to designate any one of these remains as the type of 

 the genus or species," and he remarks in speaking of the two better preserved specimens that 

 they may pertain to different species. His description is as follows: 



The two s3 T mmetrical, compact bones, represented on PI. XXI [XXII], were found separately. The lower portions of 

 their sides, as well as their ends, consist of sutural surfaces, indicating 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. 



In the larger specimen (Cat. No. 515)" the anterior end is produced forward and is slightly elevated, terminating in two- 

 projections; the surface is here distinctly nodose. In .the lateral posterior upper surface a similar rugosity is apparent. The 

 surface of the central convexity is smooth. In the smaller specimen (Cat. No. 1423) the upper surface is smooth and pitted 

 throughout. It is trilobed posteriorly and is not produced forward in front, where, however, two small nodes occur, one on 

 each side of the median line. 



The structure of the lower surface is marked by a number of smooth, concave areas, as represented in the reproductions,, 

 from photographs of the specimens, in figs. 2 and 5 of PI. XXI [XXII]. 



It is probable that these bones were situated in the median line of the head, in advance of the nasals. They may have 

 belonged to a species of dinosaur not otherwise represented in the collections from Red Deer River and, judging from the 

 difference in shape of the two specimens, more, than one species may be indicated. Marsh in his figure of the head of Triceratops 

 serratus shows a nasal horn core (divided both transversely and longitudinally by sutures) b that may correspond to the speci- 

 mens from Red Deer River. 



A third specimen (Cat. No. 1594), similar to the anterior half of the larger of the two bones, was collected in 1901. It has. 

 separated from its posterior half along the line of the transverse suture. 



For these bones the name Stegoceras validus is proposed with the hope that future discoveries may aid in a clearer under- 

 standing of their affinities. (See also Cat. No. 1075.) 



Belly River series, Red Deer River. 1898, 1901 . 



After a careful study of the materials upon which the present genus and species were 

 based I am fully convinced that they pertain to a reptile hitherto unknown. I can not, however, 

 agree with Lambe's determination as to the position which these elements occupied in the skull, c 

 nor do I believe that they pertain to any member of the Ceratopsia. And it has yet to be shown 

 that they belong to any dinosaur. I should not be surprised if, when the true nature of the ani- 

 mal to which they pertain is known, it would prove to belong to some other reptilian order. As. 

 suggested by Lambe I am inclined to the opinion that the two better preserved specimens 

 belong to different species, but I can not agree with him in interpreting them as prenasals. 

 They appear to me rather as representing the superior portion of the occipital, parietal, and 

 frontal segments of the skull of some reptile in which, as shown in fig. 99, the different bones of 

 this region have been greatly reinforced from above by the coalescence of dermal ossifications 

 which rise in a dome-shaped mass above the brain case, completely enveloping the cranial 

 elements of this region and thus giving great additional strength to the cranium. This ossified 

 dermal covering, as it might be called, differs in structure from the ordinary membrane bones 

 forming the roof of the brain case to which it is" attached in being extremely dense and in exhibit- 

 ing a columnar structure, so that about the margins this dome-like mass of bone, overlying and 

 firmly coossified with the ordinary cranial elements, is seen to be composed of innumerable 



a Mr. Lambe considers No. 515 as the type. — R. S. L. 



& These sutures separate the nasals and premaxillaries; the horn core is absent.— R. S. L. 



c In a paper published since the death of Hatcher (Trans. Roy. Soc. Canada, 2d ser., vol. 10, sec. 4, p. 24) , Mr. Lambe says: " Stegoceras 

 validus is based on portions of the skull from the median line of the head, with indications on the upper surface of the presence of an unpaired 

 horn. These parts were supposed to be prenasal, but, as pointed out by Nopcsa (Ueber Stegoceras und Stereocephalus, von Franz Baron 

 Nopcsa, jr., Centralblatt fur Mine r alogie, etc., No. 8, 1903, Stuttgart), they probably represent the frontal and nasal elements of the skull. In 

 Stegoceras we have an entirely new type, a unicorn dinosaur remarkable in that it bore a horn springing from the fronto-nasal region,, 

 recalling a somewhat similar development in the mammals Aceratherium incisivum and Elasmotherium sibiricum." — R. S. L. 



