108 I^K- E. RAT LANKESTER ON THE 



In addition to the great pe(;uliai'ity of their general form, to ^vhich allusion has been 

 already made, tlie jaws of both ^Elurus and ^Fl/iro/j/fsdiSi^v from the Ursine mandible by 

 the very reraarkal)le conformation of the condyle. 



In the condyle of Ursus the articular surface forms a regular semicylinder, with its 

 inner margin approximately at right angles to the hmg axis. On the other hand, in the 

 two genera under special consideration the articular surface is like a riband wound 

 obliquely on a cylinder of which the ends have been cut off along the margins of the 

 riband. Consequently the inner margin of tlie articular surface forms an angle of about 

 45° with the axis of the condyle. No marked ajiproximation to this very peculiar type of 

 condyle is exhibited by the Raccoon. In ^El /frits the mandibular " angle " is fairly well 

 developed and nearly continuous with the long axis of the jaw, but in ^Eluropus it is 

 very small and inflected. 



As regards the appendicular skeleton, concerning which no description has hitherto 

 ])een published, the scapula in the Museum specimen of ^Eluropus being wanting, 

 comparison may be commenced with the humerus, which has the proximal epiphysis still 

 separate from the shaft, thus indicating that the animal was not fully adult at the time 

 of its death. Compared with the corresponding bone of Ursas (PI. 20. fig. 4), as 

 well as with that of the extinct Hycenarctiis, tlie humerus of ^Eliwopus (PL 20. fig. 1) is 

 broadly distinguished by the presence of an entepicondylar foramen, in which respect it 

 resembles ^Eliirus and the American Procyonidie. But this is by no means the only point of 

 difference from the one type and aj)proximation to the other. To begin with, the head 

 of the humerus in ^Elwojms, ^Elurus, and Vrocyou is much larger in j)roportion to the 

 rest of the bone than is the case in Ursus. Moreover, in the two genera just named the 

 inner margin of the deltoid crest forms a nearly straight line, and the j^i'ofile of the front 

 surface of the bone makes a slight but regular curve. 



In Ursus, on the other hand, the inner margin of the deltoid crest is sinuous, and the 

 profile of the bone at the inferior termination of that crest (which forms a marked 

 rugosity) is angulated. In these respects the Frocyon humerus is nearer to the ^Elurus 

 than to the Ursus type. Inferiorly tlie humeri of ^Elttropns, ^Eliiriis, and Procyon have 

 a marked general resemblance, especially shown by the flatness and expansion, the shal- 

 lowness and width of the glenoid fossa, and the large size and tliitiuess of the entepicondyle, 

 which is most expanded in ^Eluropits. In U'rs/is the whole extremity is much less 

 expanded, the entepicondyle mucli more thickened from back to front, and the glenoid 

 fossa much deeper. 



As regards the second segment of the arm, the most striking feature in both ^ElurojJii'S 

 and ^Elurus is its extreme relative shortness, the ulna being considerably inferior in 

 length to the humerus, whereas in both the other two genera it is longer. As regards 

 form, the most noticeable feature in the ulna of ^Eluropus and ^Elurus is the much 

 greater elevation of the oleci-anon above the summit of the greater sigmoid notch when 

 compared with the corresponding bone of Ursus. Although the elevation in Frocyon is 

 less than in the two first-named genera, it is great(!r than in the third. The radius is, 

 however, perhaps a more important bone in respect to the differences separating Ursus 

 from the two genera specially under consideration. In the former (PI. 20. fig. 7), in 



