124: R. S. Lull — Cretaceous Armored Dinosaur, 



subdermal ossicles, the last bearing a characteristic textile 

 appearance, also present. Skull and neck region unknown. 



Relationships tvith other genera. — This genns was first 

 described in 1889 and therefore takes priority over every 

 other genus of plated dinosaurs in North America, save 

 only the aberrant Stegosaurus, to which it is but remotely 

 related. As the type is now made known as fully as may 

 be, it must be the point of departure for all subsequent 

 description of the related genera. Of these, Hierosaurus 

 Wieland shows no point of generic distinction, as the 

 common elements of each specimen are nearly identical. 

 The latter genus is founded on very uncharacteristic 

 material and is of questionable generic differentiation; 

 specifically the form //. sternbergi is doubtless distinct. 



Hoplitosaurus Lucas again is based upon insufficient 

 material for absolute distinction from Nodosaurus, as in 

 the armor the elements common to both types are 

 essentially similar. The femora differ mainly in the form 

 of the great trochanter, but as this is somewhat conjec- 

 tural in Nodosaurus, there may not be even here a very 

 marked distinction. Nodosaurus textilis and Hoplito- 

 saurus marshi, while very nearly the same size, are again 

 surely specifically distinct, and possibly generically, 

 although closely related. 



Stegopelta Williston differs from Nodosaurus in its 

 much smaller size, but especially in the development of 

 the armor over the ilia, in which there is so close a union 

 that the two are inseparable. The armor consists of 

 closely united but clearly defined hexagonal plates, each 

 with a low eminence which is, however, occasionally 

 almost obliterated by a more or less circular and irregu- 

 larly placed depression which may have been the seat of 

 a spine-like element. In the character of these iliac 

 armor plates Stegopelta seems to be unique. 



With Ankylosaurus Brown, on the other hand, a very 

 close relationship apparently existed, some of the 

 evidence for which I am not at liberty to publish through 

 courtesy to Mr. Barnum Brown, whose discovery of this 

 interesting type gives him prior descriptive rights. 

 There are, however, certain characters which render them 

 generically distinct, but I see no reason for excluding 

 Nodosaurus from the direct ancestry of Ankylosaurus, 

 nor the latter from the family Nodosauridse, the descrip- 

 tion of which preceded that of the Ankylosauridse of 

 Bro^vn by nearlv a score of years. Brown says (1908, 

 p. 190) : 



