FAUNA OP THE GOSAU FORMATION. 



637 



me to show that Struthiosaurus was probably a Scelidosaurian, and to 

 open up a suggestive possibility of its claim to the jaws and teeth 

 which have a Scelidosaurian character. Euture researches may 

 possibly demonstrate it to be the skull of Cratceomus ; but as the 

 back of the skull of Struthiosaurus is so different from that of Sceli- 

 dosaurus, I have not felt justified in adopting such a view. 



Crat^omus. 



The dermal armour of this genus presents a remarkable resem- 

 blance to that of the Scelidosaurian Dinosaurs. The large supra- 

 vertebral scutes of the caudal region are compressed, and terminate 

 upward in a sharp knife-like edge. They are, perhaps, more like 

 the similar scutes of Scelidosaurus than those of Acanthopholis. The 

 flat dorsal scutes which were carried on the ribs were also keeled ; but 

 the keel was relatively lower, and the plates were more or less ovate. 

 This, too, is a character paralleled in Scelidosaurus ; but there are 

 also scutes without any ridge at all, and marked with deep vas- 

 cular grooves. These I regard as probably ventral. Coming probably 

 from the region of the shoulders are two remarkable scutes which 

 are quite unlike any thing at present figured. These plates, which 

 are excavated on the underside, terminated in a sharp spine at each 

 end ; and the middle of the scute bore upon its surface a number of 

 conical ossifications, which have much the appearance of a group of 

 limpets packed close together. These ossifications have exactly the 

 appearance of the scutes of Hylceosaurus, so much so as to suggest a 

 doubt whether the armour hitherto referred to Hylceosaurus may 

 not be unankylosed scutes separated from the plate which carried 

 them, and really referable to Polacanthus, in which Mr. Hulke has 

 found an armour closely approximating to that seen in this genus. 

 Finally, there is a scute bearing a bone exactly like the horn-core 

 of an ox ; this I am also disposed to refer to the fore quarters. The 

 distinctive features of this armour are the sharpness of the caudal 

 scutes and the form and patelloid incrusting of the cervical scutes ; 

 but in other characters it approximates to the genera already 

 named. 



The vertebral column is remarkable for the forward extension of 

 the neural arch in the neck and the deep gap between the anterior 

 and posterior zygapophyses, the shortness of the neural spine, and 

 the biconcave form of the vertebrae, while the dorsal vertebrae are 

 remarkable for the great strength of the ridge below the transverse 

 processes, the distinctness of the facets to which the ribs were arti- 

 culated, and the broad rounded base to the vertebrae. The caudal 

 vertebrae have somewhat the form characteristic of Acanthopholis, 

 having a groove in the middle line of the base ; but the single lateral 

 ridge is a point of distinction, though the vertebrae were obviously 

 nearly allied to those of that genus. The ribs, in having the superior 

 margin flattened and widened to a greater extent than the depth of 

 the bone, present a character that is found in all reptiles which 

 carried heavy armour, but is especially characteristic of this form, 

 though, according to Mr. Hulke, met with also in Polacanthus. The 



