104 THE EXTINCT BATRACHIA, KEPTILIA 



Left Femur. — The bead and summit of the great trochanter, and the posterior portions of the condyles, are broken 

 away. The shaft is rather slender, and is strongly arched forwards and slightly outwards. The third trochanter is 

 on the posterior face, is turned inwards, and marks one-third the length of the shaft from the supposed position of 

 the head. Just below it the shaft is cyclo-trigonal, while for a short distance above the condyles it is flattened ante- 

 roposteriorly. It is strongly concave between the condyloid ridges at the distal end. At this place the external face 

 is convex, the internal concave as high as a point a little more than a fourth the total length. The concavity is sepa- 

 rated from the anterior face by a strong ridge which is partly broken away. The anterior surface is turned posteriorly 

 to the external condyle, while it is concave and turned forwards to the internal condyle. 



The posterior portions of the two condyles are broken away, so as to give their remaining portions almost exactly 

 the form of the head of the femur in Hadrosaurus and Iguanodon. The dense layer of the remaining portions is 

 much worn away, but enough remains to show that the external was rather the more prominent. The trochlear and 

 popliteal concavities approach much nearer together than in Megalosaurus, causing a greater attenuation of the 

 basis for the condyles. It cannot be ascertained whether the external condyle bore the small process behind seen in 

 Megalosaurus. 



The neck is much compressed anteroposteriorly, and extends much interior to the line of the shaft. The poste- 

 rior face is regularly convex, and then turns into the transversely convex exterior, which is divided above by the 

 groove that separates the external trochanter. The broad posterior face narrows below this trochanter, and presents 

 a strong convexity posteriorly, opposite the upper portion of the third trochanter. The outer trochanter has a flat 

 anterior face, and presents a sharp margin inwards. It is separated from the neck by a deep longitudinal concavity. 

 It is probably much shorter than the head of the femur, about as in Megalosaurus. 



In. 

 Length of femur restored, 35.5 



" actual, 32. 



Transverse extent of condyles, 6.45 



Posterior breadth of neck, 6.5 



Anterior " of great trochanter, 3.25 



Diameter neck and " " 4.5 



" anterior groove between them (medially), 1.5 



Circumference shaft at middle, 11. 



This element, compared with that of Megalosaurus, differs in its considerably more slender form, and in its curva- 

 ture. The femur of the latter genus is very stout, and has a straight axis. The posterior prolongations of the 

 condyles are broken away, but if the external were as small as in Megalosaurus, it was more external, and the poplit- 

 eal concavity not so abruptly distinguished from the posterior face of the shaft above. This extremity of the bone 

 more nearly resembles that of the Poecilopleurum bucklandii, described and figured by Deslongchamps. 



In my original description (Proc. A. N. Sci., 1866) I reversed the position of this bone, I believe incorrectly, 

 which has been observed by Leidj'. As it stands broken, the distal extremity is almost identical with that of Hadro- 

 saurus, and the proximal with the trochanter furnishes a very good basis for condyles like tbose, of Megalosaurus; 

 hence the error. 



The relative lengths of the femur and humerus of certain genera of this order may be compared as follows: — 



Iguanodon anglicus, 

 Hadrosaurus foulkei, 

 Laelaps aquilunguis, 

 Poecilopleurum buekiandii, 



Left Tibia. — The tibia is more slender than that belonging to Megalosaurus described by Prof. Owen, and the 

 distal articular surface, instead of being lozenge-shaped, is cuneiform, the inner wide extremity oval rounded. Inner 

 transverse breadth of proximal head one fourth total length. Anterior crest very strong, much incurved, disappear- 

 ing at between the proximal fifth and fourth of length; internal ridge on proximal half, strong, but not reaching 



?0 



Humerus. 



Femur. 



Pr 



o'portion. 



19 



S3. 





.575 



22.5 in. 



41.5 





.54.2 



12 in. 



35.5 





.33.8 



13 



38 







