N-0. 2.J COPE ON MIOCENE RODENTIA. 383 



nation, and projects well within the internal face of the shaft. Its articu- 

 lar surface is prolonged towards the great trochanter. Fosm ligamenti 

 teris isolated. The distal extremity of the femur exhibits the superiorly 

 prolonged patellar groove characteristic of this group of rodents. The 

 condyles are more than elsewhere produced downwards and posteriorly, 

 and are well separated. 



The spine of the tibia is rudimental, and the crest is very obtuse. The 

 inferior continuation of the latter forms a prominent reverted keel on 

 the proximal front of the shaft, which is deeply concave on its inner 

 side. The posterior face is also concave and is separated by a lami- 

 nar external bone from the external side. The external border of the 

 head is not deeply notched as in Panolax. The fibula unites with the 

 tibia on the proximal part of the latter. The remainder of the shaft is 

 smooth. The external malleolus is large and at right angles to the long 

 diameter of the distal end of the bone, and its extremity is a facet for 

 contact with the calcaneum. On its external face is a prominent process 

 directed backwards. The external trochlear groove is deeper than the 

 internal, and is well separated from it. The internal malleolus can 

 scarcely be said to exist. It may be represented by a small process on 

 the inner side of the extremity of the shaft. 



The astragalus is elongate and flat, and the trochlear portion is ob- 

 lique. The neck is elongate, and convex on the inner side; the con- 

 striction is on the inner side immediately behind the head. The long 

 diameter of the latter makes an angle of 45° with the horizontal plane. 

 The external trochlear arc is much larger than the internal. The coty- 

 1ns, which fits the external condyle of the calcaneum, posesses a peculiar 

 impressed area on its posterior surface. The calcaneum extends nearly 

 as far anterior to its condyle as posterior. The free portion is subcylin- 

 dric or subquadrate to the end. The internal process for the astragalus 

 is quite prominent. The cuboid facet is directed obhquely inwards, 

 running into a short longitudinal groove. The cuboid extremity is little 

 depressed. 



The skeletal characters above enumerated were taken from the bones 

 of P. turgidzis and P. haydeni, excepting in the cases of the ulna, radius, 

 ilium, and calcaneum, which were derived from those of P. haydeni only. 



A cast of the cranial chamber of a specimen of Palaeolagus haydeni 

 displays the superficial characters of the brain. As in the order gen- 

 erally, the hemispheres are small and are contracted anteriorly. The 

 greater i^art of the cast of the cerebellum is lost, but enough remains to 

 show that it was large. The olfactory lobes arc large ; they are not 

 gradually contracted to the hemispheres, but expand abruptly in front 

 of them, being separated by a constriction only. They are wider than 

 long, and than the anterior extremity of the hemispheres. Their cribri- 

 form surface is wide, and extends backwards on the outer sides. Traces 

 of the three longitudinal convolutions can be observed on the hemi- 

 spheres above the lobus liipiwcam^i. The internal and median are con- 



