SKELETON OF RODENTIA. 



379 



■•^c^ 244 



projects beyond the tibia, and a 'fabella' is wedged between it 

 and the outer condyle of the femur ; there is a similar sesamoid 

 behind this condyle, and a third behind the inner condyle. The 

 patella is ossified. 



The tarsus shows the naviculare, astragalus, calcaneum with a 

 long lever : the meso- and ecto-cuneifomi bones, and the cuboid. 

 There is a supplemental ossicle be- 

 neath the astragalus. The navicu- 

 lare has a large process. The inner 

 digit is wanting, and the base of the 

 metatarsal of the second is extended 

 backward, like an entocuneiform, to 

 join the naviculare. 



In the Hare-like Cavies of South 

 America {Dasi/procta) the cla^dcles 

 are represented, as in the Hares, 

 by slender ossicles : the supra- and 

 infra-spinal fossa? of the scapula are 

 of equal depth : the humerus is per- 

 forated between the condyles : the 

 radius and ulna have become anchy- 

 losed, reducing the interosseous space 

 to a narrow chink near their proximal 

 ends in the Acouchy : in an Agouti 

 I found this confluence not complete. 

 The fore foot is pentadactyle. The 

 first row of carpals is formed by the 



scapholunar, the cuneiform, and a large pisiform. There is an 

 termedium ' between the os magnum and trapezoides. The pollex 

 is shorter in the Agouti than in the Acouchy. The fifth finger 

 is much reduced in size, but has the normal number of phalanges. 

 The ungual phalanges are notched at their apex. The femur 

 gives a feeble indication of the third trochanter at the middle of 

 its outer side. The tibia and fibula are distinct ; a fiibella is 

 attached to each femoral condyle. The foot has but three digits. 

 The long entocuneiform bone has coalesced with the inner side of 

 the metacarpal of the second toe — here the innermost. Tlie 

 supplementary ossicle crossing the articulation between the astra- 

 galus and scaphoides is present. There is a distinct sesamoid 

 beneath the joint of the cuboid with the external metatarsal {iv): 

 both the naviculare and cuboid send strong processes to the 

 plantar side of the tarsus. There are trochlear sesamoids beneath 

 the metatarso-phalangial joints : the ungual phalanges are notched. 



Pelvis of tlie Hare, anterior view. 



in- 



