BY PROFESSOR STEPHENS, M.A., F.G.S. 15T 



which gives an imperfect head, with some of the details in a good 

 state. Example No. 1 is a little over a foot in length, broken off 

 at the tail end, and apparently made np to some extent about the 

 snout. For the collector, afraid that the soft and perishable nature 

 of the stone might lead to the obliteration of important details, has 

 applied a kind of black japan to the surface, doing no harm in 

 some cases, but in others, as in this, quite destroying the outlines, 

 which very probably were originally faint, or perhaps injured in 

 the quarry. This rendei's the mea.surements from the snout 

 doubtful, though they cannot be far out. The orbits ai'e very 

 distinct, and show that the fossil has been a little distorted by 

 downwai'd and forv^^ard pressure from the right, lying as they do 

 to the other side of their true position, and with the right orbit 

 a little in advance of and rounder than the left. The post orbital 

 bones are in good relief, ending in acute angles towards the back of 

 the head. A flattish medial depression in the parietals seems to 

 indicate the place of the foramen, which may probably be deter- 

 mined by careful use of the knife, but which I cannot at present 

 distinguish. The super-occipital is completely ossified, extending 

 as far back as the anterior portion of the thoracic plates, and 

 closing the intervening space shown in Vol. XI. pi. xxii. of our 

 Proceedings. The quadrato-jugals are prolonged far to the rear of 

 their position in the younger specimen, (ibid. p. 1182), and the 

 branchial arches (if present) ai-e obscurely indicated between these 

 backward processes and the clavicular plates. The vertebral 

 column is represented by an indistinct ridge extending about half- 

 way down the whole length of the fossil, and pushed a little 

 towards the left. I can see no traces of ribs, limbs, nor of any 

 structure more than has been mentioned, except that the dermal 

 covering of the head seems to be preserved, presenting an irregu- 

 gularly pitted or granulated surface, the ' grain ' averaging about 

 1mm. across. As in the former example, it is the inner or upper 

 surface of the thoracic plates that is presented, and the outer or 

 upper surface of the head. 



It is curious that both this and the former specimen should 

 have fared alike in this respect. Both of them preserve and 

 expose the upper surface of the head, and both have lost all the 

 structures overlying the Thoracic plates. The preservation of the 

 head is no doubt owing to its more perfect ossification ; and the 



