MUE^NOSAUEUS. 119 



convex and clearly had a thick cap of cartilage in life. The trochanter (t)\) arises 

 from the dorsal surface just beneath the head, with which its upper end is continuous, 

 the two making an angle of about 110° with one another. In outline the upper end of 

 the trochanter is roughly quadrangular, but in some cases it is divided into a larger 

 anterior and a smaller posterior portion by a deep groove running down its postero- 

 superior face. The shaft is nearly circular in section, and the ventral surface of its 

 upper half is much roughened for muscle-attachment {r.m.), and there is also a strong 

 roughened ridge about the middle of the posterior border of the shaft. As already 

 mentioned, the distal expansion is less than in the humerus, and the cartilage-covered 

 terminal surface is not carried on to the postaxial and preaxial borders by the 

 expansion, as in that bone. The surface of the bone has the same fibrous appearance 

 noted in the case of the humerus. 



Two bones only (the tibia ar\d fibula) articulate with the distal end of the femur. 

 Both are flattened polygonal bones, which articulate with one another by short 

 proximal and distal surfaces, being separated in the middle by a foramen. Their 

 surfaces for union with the femur are gently convex, so also to a greater degree are 

 their outer borders. Distally the tibia (t.) bears a long facet for union with the tibiale 

 (tib.) and a short one for the intermedium (int.), while the fi.bula {/.) joins the inter- 

 medium and fibulare {fib.) by facets of about equal length. The proximal tarsals are 

 polygonal flattened bodies ; the tibiale [tib.) unites distally with the first and second 

 distal tarsals, the intermedium [int.) with the second and third, the fibulare [fib.) 

 with the third and with the fifth metatarsal. The postaxial border of the fibulare is 

 thin and concave. There are five metatarsals, the first borne exclusively by the first 

 distal tarsal, the second by the first and second, the third by the second and third, 

 the fourth by the third only, wliile the fifth, as already noted, articulates directly 

 with the fibulare, just as the fifth metacarpal does with the ulnare. The metatarsals, 

 especially the first, are somewhat flattened from above downwards, but the phalanges 

 are cylindrical, with constrictions in the middle ; the terminals may be mere 

 nodules of bone. In the best paddle preserved (text-fig. 63, A) the numbers of the 

 phalanges in the digits from the first to the fifth are 6, 13, 15, 13, 9, respectively. 



Text-figure 66 is a semi-diagrammatic restoration of the skeleton oi Micrcenosaurus, 

 in which an attempt is made to represent the skeletal characters described above, and 

 at the same time to give a general idea of the form of the animal as a whole. The 

 chief points of interest are the relatively small size of the head, the great length of 

 the neck, and the slight degree to which the distal end of the humerus is expanded 

 compared with that of Cryptocleidus : the peculiar characters of the shoulder-girdle and 

 pelvis cannot be shown in a profile view. The reconstruction is founded mainly on 

 the skeleton of the type specimen of Muroenosaurus platyclis (E. 2678). 



