Vol. 56.] 



SKELETON OF EUEYCAEPUS OWENI. 



331 



known impression of the underside. As the digits are preserved, 

 the interspace between the second and third digits is slightly greater 

 than between the others. The number of bones in the fingers 

 appears to follow the formula 2.3.3.3.3. It was already known 

 that the terminal claw-phalanges were elongated and conical, but 

 the middle one is 0*7 inch long, and longer than the two preceding 

 phalangeal bones. They are all more or less rounded on the upper 

 surface, but the first is obliquely flattened on the inner aspect, and 

 the fourth and fifth are much more compressed from side to side 

 than the second and third, and more arched from front to back. 

 There is a mark in the slab prolonged beyond the fifth claw, and 

 others for a length equal to the bone, which may indicate the original 

 extent of the horny claw (PI. XXI, H). The length of the claws 

 and the mobility of the joints in the fore-limb, no less than the 

 form of the bones, are suggestive of a burrowing habit in this 

 animal. 



The Hind-limb. (Fig. 4.) 



The femur was very imperfectly preserved in the Bain slab, 

 where it appears to be 4*4 inches long, and to have the proximal 

 articular head directed inward in a way which may approximate 

 to the form of the bone in known Theriodonts. This specimen 

 shows that the distal end of the femur 

 (PL XXI, F) was subquadrate, not more 

 than 1 inch thick, flattened on the inner 

 and hinder surfaces, with the distal surface 

 rounded a little from front to back, but so 

 truncating the bone as to show that the 

 femur may have been carried in a more 

 vertical position than is usual in living- 

 reptiles. Its form approximates to the bone 

 which I have regarded as the femur of Rho- 

 palodon more than to that of Cynognathus. 

 The tibia and fibula are well displayed 

 in the Murray slab. There is the same 

 slender mammalian proportion of fibula 

 which has already been detected in Micro- 

 gomjoJiodon, and this appears to be a 

 Theriodont character. This segment of the 

 hind-limb is 3'7 inches long. 



The tibia is slightly enlarged at the 

 distal end, where it measures y^- inch from 

 side to side, and appears to terminate in a 

 truncated articular surface, with the border 

 slightly rounded. The proximal end is 

 more expanded, and its width is 1*2 inches. 

 The posterior margin of the shaft is more 

 concave in length. The bone shows some evidence of compression, 

 especially towards its extremities. The proximal extremity consists 

 of two surfaces which are inclined to each other at a large angle. 

 The smaller posterior surface is terminal and articular, and 



pig. 4. — Tibia and 

 fibula o/Eury carpus 

 Oweni {about § not. 

 size). 



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