1871.] HULKE REPTILIAN SKULL. 201 



processes. These in their present abraded state are obtuse four-sided 

 pyramids, the lower side of which looks downwards, and contributed to 

 form the orbit ; another side looks backwards, and belongs to the tem- 

 poral fossa ; a third is directed upwards, and forms part of the sinci- 

 put ; and the fourth, directed forwards, is part of the fractured surface 

 left by the separation of the facial segment of the skuU. Behind, the 

 temporal fossae are Kmited by the outer and anterior surface of strong, 

 trihedral, divergent, suspensorial processes (sp) directed outwards 

 and backwards, from which the quadrate bones depended. The roof 

 of the skuH in front is broad and transversely convex, and above the 

 middle of the temporal fossse it contracts so much that here it might be 

 properly described as crested {pa), the sides sloping almost vertically 

 from the mid ridge, with only a slight outward inclination, as low as 

 a horizontal groove running from front to back along the temporal 

 fossa, and marking, perhaps, the meeting of the lower border of the 

 parietal bone with those forming the side-walls of the skull. Behind, 

 the narrow crested part of the roof forks and sends outwards and 

 backwards the usual divergent parietal processes of lacertilian skulls. 

 An obscure serrated transverse line about -5 inch behind where the 

 facial segment has broken away is, perhaps, the suture between the 

 parietal and principal frontal bone. No parietal foramen is discern- 

 ible. That part of the parietal bone which roofs the front of the 

 cranial cavity is very dense ; it attains a thickness of -9 inch. The 

 hinder part of the roof is even thicker, but it is much less solid and 

 consists principally of cancellous tissue. 



Yiewed from behind (fig. 4), the outline of the skull is an inverted 

 triangle. The left suspensorial process, forming the upper and outer 

 angle, on this side'^is wanting ; and the end of the right one (sp) is 

 abraded. On the right side the whole of the surface above the fora- 

 men magnum is much splintered ; but the splinters having become 

 reunited with very little displacement, its form is not much changed. 

 When the floor of the cranial cavity is horizontal, the part of the occi- 

 pital surface immediately above the level of the foramen magnum looks 

 downwards and backwards, while the greater part of the surface above 

 this looks upwards and backwards, and it makes now an obtuse angle 

 with the sinciput ; but as the meeting line of the occiput and sinciput 

 is somewhat crushed in and worn, the angle may originally have been 

 much smaller. This incrushing has been favoured by the presence 

 here of the cancellous tissue already mentioned. The foramen mag- 

 num (/) is subcordate (ia the language of botanists). Its vertical 

 diameter is 1-4 inch, and its transverse one 1-6 inch. Directly above 

 the foramen is a slight mesial swelling, from which a low horizontal 

 ridge is produced outwards. Laterally, below this ridge the surface is 

 gently hollow. The occipital condyle {ot) roughly resembles a horse- 

 shoe. Its upper surface is deeply grooved. Its transverse slightly 

 exceeds its vertical diameter. It projects considerably behind the 

 general plane of the occiput ; and below, at the under surface of the 

 skuU, a deep constriction separates it from the parts immediately in 

 front, making it nearly pedunculated. 



The base of the skull (fig. 5) offers an extremely irregular surface. 



