666 



PROF. H. Gr. SEELEY OX THE REPTILE 



The lateral trochanter is placed, as usual, at the angle between 

 the internal and posterior aspects of the bone (fig. 4). It is moderately 

 elevated, about 1-J inch long, -f- inch wide proximally, aud tapers 

 distally ; it is placed exactly midway between the proximal and 

 distal articular ends. Below the trochanter the section of the shaft 

 becomes subtriangular, being flattened on the internal aspect and 

 posteriorly, and rounded on the external and anterior aspect. 



The distal articulation is chiefly noticeable for the inflated expan- 

 sion of the bone at the external margin, and for the relatively large 

 size of the condyles (fig. 4). The articular surface is 3 inches long in 

 the left femur, which has this region best preserved ; it is very mode- 

 rately convex from behind forward, and very slightly concave from 

 within outward, and rounds gently into the anterior surface of the 

 bone, where a concave natural impression divides the anterior 

 margin into a larger internal area and a smaller area which is 

 external. There is the usual ill-defined gently concave pit for liga- 

 mentous attachment just above the articulation on the flattened in- 

 ternal surface of the bone, which looks obliquely upward, much as 

 in Cryptosaurus. The internal condyle is the larger of the two ; it 

 is about an inch wide, and curves round considerably on the posterior 

 aspect of the bone, so as to cause the articulation to measure 2-^- 

 inches from front to back. The interspace between the condyles is 

 about T § - inch ; and in this region the articulation measures, from 

 front to back, inch. This depression becomes prolonged up the 

 middle of the posterior side of the shaft towards the inner part for 

 about 1^ inch. The smaller condyle is more compressed, about 

 T 6 ^- inch wide, and gives an antero-posterior measurement to the arti- 

 cular end of 2 inches ; and external to this condyle is a concave area or 

 groove, \ an inch wide, which defines it from the well-rounded broad 

 external margin. The small part of the articulation external to this 

 condyle makes a considerable angle with the major part of the sur- 

 face. The anterior * half of the articular surface is nearly smooth ; 

 but the posterior half is deeply scored with about eight comparatively 

 straight grooves, six of which lie between the condyles. These 

 grooves appear, from their corresponding development at the anterior 

 part of the proximal articulation, to be in the positions of greatest 

 pressure and greatest condylar growth, and may be regarded as evi- 

 dence that the bone was carried in an oblique position, as among 

 mammals. 



Tibia. 



A smaller pair of tibial bones are much less perfectly preserved 

 than those of the large species, onlv exhibiting about 6J inches of 

 the middle of the shaft (PI. XXVII. fig. 19). Their ends are 

 decayed in the usual way ; and distally the fractured outline was 

 subtriangular, but formed a triangle in which the anterior and two 

 converging posterior elements rounded into each other, and were 

 subequal. Here the extreme antero-posterior measurement is 

 about 1^- inch, and the extreme width from side to side at the 

 distal end is the same. In the middle of the shaft the antero-posterior 



