TEICLEIDUS SEELETI. 161 



The radms (r.) is considerably larger than the ulna ; it articulates with the 

 humerus by a long oblique and nearly straight facet ; its outer border is thin and 

 rounded, while the inner bears two facets for union with the ulna, one proximal, the 

 other distal, the two bones being separated in the middle by a rounded foramen. 

 Distally the radius articulates with the radiale by a long facet, and behind this, and 

 making an obtuse angle with it, there is a short facet for the intermedium. The 

 idna (u.) has a nearly flat facet for the humerus ; anteriorly it unites with the radius 

 at its proximal and distal ends, being separated from it in the middle by the foramen 

 mentioned above. Distally it joins the intermedium and ulnare, the facets for 

 which make with one another an angle a little larger than a right angle ; postaxially 

 it unites with the jaisiform (p.). This bone articulates proximally with the humerus, 

 anteriorly with the ulna, and distally with the ulnare ; it also has a short facet on its 

 posterior border for contact with the accessory ossicle [a.). This is an elongated bone 

 which unites by a long facet with the postaxial border of the distal expansion of the 

 humerus, and, as above noted, its lower end is in contact with the pisiform. 



The form and arrangement of the carpal bones will be best understood from the 

 figTire (text-fig. 77). There are three carpals in each row, those in the distal rows 

 being small ; the fifth metacarpal {mc.V), as usual in these reptiles, articulates with the 

 ulnare and has on its preaxial face at the proximal end a facet for contact with the 

 third distal carpal. 



The otlier metacarpals articulate proximally as follows : — metacarpal I. with the first 

 distal carpal only ; metacarpal II. with the second carpal ; metacarpal III. partly with 

 the second and partly with the third carpal ; metacarpal IV. with the third car[;al 

 only. 



Of the pelvis only a pubis is known. This is a broad plate of bone, the length and 

 breadth of which are almost equal, in this respect resembling the pubis of Murcenosaurus 

 rather than that of Cryptocleidus, which is considerably wider than long. The greater 

 part of the bone is thin, but it thickens towards the symphysial border, the symphysial 

 surface being rather deep, especially towards the front. The articular region is also 

 much thickened and bears two subequal facets, one for union with the ischium, the 

 other forming the anterior part of the acetabulum ; as usual, there is no contact with 

 the ilium. The anterior edge of the bone is somewhat irregular in outline, net being 

 evenly convex as in some Plesiosaurs ; the visceral surface is slightly concave, the 

 outer surface flat or slightly convex. 



The femur (PI. VIII. figs. 4, 4 «) is a much more slender bone than the humerus, 

 but of about the same length. The head (A.) is convex, and the trochanter {tr., fig. 4 a) 

 is very strongly developed, its upper surface being continuous with that of the head 

 xlnteriorly it is bounded by a strong ridge, but the ridge forming its posterior border 

 is not so strongly marked. The ventral face of the upper half of the shaft bears a 

 much roughened surface [m.r.) for muscle-attachment, and most of the posterior face 



Y 



