532 BRITISH FOSSIL REPTILES. 



but this may be due to fractiu-e. The superoccipital develops a tuberosity at each upper 

 angle, near its junction with the mastoid, 8. Each exoccipital swells at its outer border 

 into two tuberosities, representing the paroccipitals of Chehnia, and contribiiting to the 

 articulation for the tympanic, 28. The direction of the bilobed paroccipital border, 4, is 

 oblique from al)ove downward and inward. The tuberosity forming the angle of the 

 mastoid, 8, projects distinct from the upper paroccipital one, 4. 



In the relative extent of the paroccipital tuberosities and in the direction of their 

 border HylcBochampm resembles Teleosaurus, and differs from Crocodilns, in which the 

 masto-paroccipital border extends from above downward and outward (ib. fig. 4), making 

 the greatest breadth of the occipital surface to be at the paroccipitals, not at the mastoids. 



There is no vacuity between the mastoid and supei'occipital ; a linear suture, slightly 

 concave upward, alone divides them on the occipital surface. 



The articular surface of the tympanic, 28, projects as usual, backward, beyond the 

 plane of the occiput ; the medial half only of that surface is preserved in the present fossil ; 

 it is almost vertical and very slightly convex. 



The upper platform of the cranium behind the orbits (PI. 60, fig. 24) is subquadrate, 

 with the anterior angles rounded off. It is perforated by the pair of upper temporal 

 openings, t, which are oblong-ovate, with the outer border almost straight, the inner one 

 curved, and with the hinder or basal border slightly raised; the anterior border is 

 depressed and continued upon the side of the cranium proper, forming the inner wall of 

 the temporal fossa. A flat surface of bone (s, 12), equalling the breadth of the temporal 

 opening, lies exterior to it; a narrower concave tract (11) divides the openings; the 

 posterior surface (7) is broader than the lateral ones. 



In Teleosaurus and allied genera (e. g. MetriorJii/nchus, Teleidosaurus, Steneosaurus, 

 Felagosaurus, &c.) the upper temporal openings are relatively larger and the surrounding 

 flat tract of bone is of less extent than in Hyheoclumpsa, which herein more resembles 

 the tertiary and modern CrocodUia, although the form of the openings is teleosauroid. 



The general form of the upper cranial surface posterior to the orbits resembles, in 

 Hylceochamjisa, more that in Crocodilns, Metriorhi/nchus, and Pelayosaurus, than that in 

 Teleosaurus cadomensis and in Gavialis, in which latter the breadth exceeds the length. 



The orbits in HylcBochampsa (PL GO, fig. 24, 0) are circular and better defined by 

 the post-frontal (12) from the lateral outlets (<') of the temporal fossse than in Crocodilus, 

 and herein they more resemble the orbits in Teleosaurus ; but they are less horizontal 

 than in Tel. cadomensis, and incline less to the vertical position than in Tel. [Pelayosaurus) 

 temporalis; their outline is obliquely upward and outward. The prefrontal (14) and 

 lacrymal (73) swell out a little anterior to the orbit, whence the maxillary (21) and nasals 

 (15) continue to form the upper jaw. This recalls the character of that part of the skull 

 in the Gavial rather than in the Crocodile. 



These modern or procoelian representatives of the order CrocodUia differ from the 

 Lacertilia in the greater extent or degree of ossification of the palate. 



