PICEOCLEIDUS BELOCLIS, 141 



Coll. 14). Shoulder-girdle and radius and ulna figured by Seeley, loc. cit. sujjra, 

 figs. 10-12. 



This species was distinguished by Professor Seeley on the strength of the structure 

 of its clavicular arch, and its numerous other peculiarities show that he was fully 

 justified in his conclusions. 



In the type specimen no parts of the skull are preserved, but in the case of a second 

 individual (R. 3698, Leeds Coll. 173) referred to this species, some fragments of the 

 skull and mandible are present, the chief elements being the basioccipital (still articu- 

 lating with the atlas and axis), the quadrates with part of the squamosals attached, and 

 a much crushed exoccipital. The basioccipital is much distorted, but, apart from the 

 small size, does not seem to difier in any important particular from the same bone in 

 THcleidus (p. 150). The quadrate is notable for the narrowness of the articulation 

 for the mandible, in this respect differing widely from the same part in Tricleidus and 

 Murcenosaurus, the outer convex condyles seen in the quadrates in those genera being 

 almost absent : this peculiarity is, of course, reflected in the articular surface of the 

 mandible, the outer concavity being correspondingly narrow. The postarticular 

 (angular) region of the mandible is much more slender than in the other genera. 

 A few fragments of the crowns of teeth on the back of the right ramus of the 

 mandible show that the enamel is raised into fine longitudinal ridges. 



In the type specimen only six cervicals and two dorsals are preserved, but in E.. 3698 

 all the cervicals (PI. VII. fig. 5), with the possible exception of one or two posterior 

 ones, and some sixteen caudal vertebrce, are preserved. The cervicals, including the 

 atlas and axis, are at least thirty-nine in number. The atlas and axis (PI. VII. fig. 5) 

 are closely fused together and are relatively much shorter than in Murcenosaurus and 

 Tricleidus, although their structure seems to be the same as in those genera. Both 

 atlas and axis are rib-bearing (r 1, r 2) ; the neural arch and spine are lower than in the 

 above-mentioned genera, and there is no hypapophysial ridge. The posterior face of the 

 axis is gently concave and is much wider than high, characters that are also present in 

 the centra of the other cervical vertebrae. In these the centra are considerably wider 

 than they are long, and their upper surface is deeply grooved by the floor of the 

 neural canal (figs. 4, 5 «, 5 h). The neural spines are low and inclined backwards 

 in the anterior region, but further back they become more upright and at the same 

 time broad and high (PI. VII. figs. 3, 4, 5). The anterior cervical ribs have a well-marked 

 anterior process [a.]).), which further back is reduced to a slight angulation on the 

 front of the rib. Two anterior dorsals are preserved in the type specimen : in these 

 the centra are wide and depressed, the ends being very slightly concave with a gently 

 raised central area. The transverse processes are very stout and strong and terminate in 

 a broad facet for the single-headed dorsal rib ; the neural arches are not well preserved. 

 Some of the caudal vertebrae are shown in the second specimen : of these the anterior 

 ones have wide low centra (PI. VII. figs. 6, 6 a) with somewhat concave ends ; on the 



