864 MB. F. 6. PARSONS Olf THE [NoV. 29, 



and evidently corresponds to the proximal joint of the same 

 structure in Pedetes. Xo signs of a distal joint are present. 



It is worthy of remark that the long axis of the distal joint of the 

 radial ossicle of Pedetes is placed at such an angle with that of the 

 proximal that its termination is situated near the root of the nail, 

 while its proximal end is opposite the free edge of the nail. I do 

 not, howe\er, think that this change in the relative position of the 

 parts is of any great importance. 



The Os Innominatum has the surfiice for the iliacus directed 

 ventro-laterally, as in the Hares. The ischial tuberosity is very 

 prominent, and the obturator foramen large and pear-shaped. In 

 the foetal bone only the three primary centres are present. 



The Femur is chiefly remarkable for the large size of the laterally 

 compressed great trochanter, at the base of which a rudimentary 

 third trochanter exists. There are two fabellse, of which the outer 

 is the larger. The femur of Dipus is practically identical, except 

 that the articular surface of the head is continued outward for a 

 considerable distance on to the upper surface of the neck. 



The Tibia is considerably longer than the femur, the cnemial 

 crest being specially prominent. 



The Fibula is transitional between the hystricomorphine type, 

 in which it is a distinct bone, and the myomorphine, in which 

 it is fused with the tibia in its lower part. In Pedetes the fibula 

 is quite free in its upper half, and from the front of the head a 

 process projects forward and inward ; in its lower half the bone is 

 closely bound to the tibia and becomes so attenuated as to be 

 barely visible ; it is, however, at no time completely merged with 

 the tibia. The external malleolus is fairly well marked, and con- 

 siderable movement is allowed between it and the tibia. In Dipus 

 the fibula becomes completely incorporated with the tibia in its 

 lower half, as it is in mouse-like rodents generally, and no movement 

 is possible between the external malleolus and the tibia. In the 

 foetal specimen of Pedetes only the centres for the shafts of these 

 long bones were present. 



The Tai'sus consists as usual of astragalus, calcaneum, navicular, 

 3 cuneiforms, and cuboid. The navicular is remarkable for having 

 a process on the plantar surface prolonged from before backward 

 and laterally compressed ; it projects anteriorly under the external 

 cuneiform and almost touches the base of the middle (3rd) meta- 

 tarsal ; between its anterior projection and the external cuneiform 

 is a tunnel for the peroneus longus tendon. The internal cunei- 

 form is prolonged forward on the inner side of the base of the 

 second metatarsal, into this projection the tendon of the peroneus 

 longus is inserted ; heuce there is little doubt that it represents the 

 aborted first metatarsal. The internal cuneiform is also prolonged 

 backward along the inner side of the navicular until it just reaches 

 and articulates with the head of the astragalus. On the inner 

 side of the internal cuneiform is a thin plate of bone with its 

 long axis at right angles to that of the foot ; its upper extremity 

 articulates with the inner side of the navicular, while its lower 



