FATJJSA OF THE GOSAU FORMATION. 



627 



itself, is convex from side to side. The unworn part of the crown 

 below is vertically striated; but the ribs are fainter than on the lower- 

 jaw tooth. The inner surface of the crown is subquadrate, marked 

 with eight vertical ridges, which are moderately elevated, stronger 

 and wider apart on one side of the tooth than on the other. The 

 height of the crown is about 8 millim., and its width about 7 millim. 

 Its thickness at the base is about 4 millim. 



Parietal bone of a small Dinosaur (probably Mochlodon). 

 (See Biinzel, pi. v. fig. 11, p. 14.) 



The parietal bone of a small Dinosaur (PI. XXX. fig. 1), which was 

 regarded by Biinzel as a Lizard, shows, as I take it, the parieto-frontal 

 suture in front, and an indication that the postfrontal bone was given 

 off from the expanded anterior outer corner, much as in Iguanodon. 

 The under and interior surface of the bone, however, is much more 

 lizard-like in some respects, seeing that it did not enclose a brain- 

 case after the pattern demonstrated in Iguanodon, Hypsilophodon, 

 Struthiosaurus, and other genera. The bone was relatively thin, but 

 appears to have been united by a not very intimate suture to bone 

 below, which formed the lateral wall of the brain-case. The bone is 

 imperfect posteriorly, being fractured ; superiorly it is divided into 

 three areas : — a median triangular area with concave sides, which 

 becomes narrower posteriorly till it disappears at about the line of 

 fracture (this surface is slightly convex from side to side in front) ; 

 and two lateral areas for the attachment of muscles working the 

 lower jaw, which converge posteriorly, and in converging are more 

 highly inclined to each other. Their superior limit is sharply de- 

 nned by a ridge, which becomes elevated posteriorly, and is appa- 

 rently passing into a median crest, and is also elevated anteriorly at 

 the point where the postfrontal suture is visible. The length of 

 the fragment is 2 centim. ; its width in front, as preserved, is 2 

 or 3 millim. more; its width posteriorly is \\ centim. There is 

 no foramen parietale. The characters are. certainly such that the 

 bone might well be referable to the skull of a Lacertilian ; but it 

 would be hazardous to determine absolutely on such evidence whether 

 the bone really pertained to Mochlodon Suessii, as is rendered pro- 

 bable by its Iguanodont form. 



Scapula {probably of Mochlodon). 



The imperfect proximal end of a small scapula (PI. XXYIII. fig. 1) 

 presents somewhat Crocodilian characters. The fragment is only 

 4 centim. long. It shows the humeral articular surface and part of 

 the sutural surface for the coracoid. The character which especially 

 distinguishes it from Crocodiles is the extraordinary lateral position 

 of the humeral articulation, in consequence of the sutural surface for 

 the coracoid being prolonged beyond it. This articular surface is 

 2J centim. long, centim. wide proximally, and narrower towards 

 the sutural surface. The bone is a little crushed, but was concave 

 from above downward, and flattened in the antero-posterior direc- 



2t 2 



