Marsh Collection, Peabody Museum. 



203 



in the Insectivora, and not posterolat- 

 eral, as in the Carnassiclentia ; the ento- 

 carotid enters the tympanic chamber 

 and divides in a manner similar to that 

 of the modern Insectivora, the main 

 branch grooving the outer lateral aspect 

 of the periotic, in front of, and below 

 the fenestra ovalis, the other passing 

 between the crura of the stapes and 

 thence into the brain case; the foramen 

 ovale is situated well within the basi- 

 sphenoid and the paroccipital process 

 projects outward and backward. There 

 is no anterior glenoid process, but a dis- 

 tinct postglenoid foramen, and a deep 

 groove in the position of the alisphenoid 

 canal ; the deltoid crest of the humerus, 

 figure 78, is little developed, the shaft is 

 much curved, and the distal end is broad, 

 with an entepicondylar foramen : the 

 ulna has a relatively short incurved 

 olecranon, and the head of the radius is 

 subcircular ; there were five toes in the 

 manus, the pollex, figure 79, unreduced, 

 and the phalanges, figure 80, elon- 

 gate as in Lutra / the femur has a 

 strong second and a weak third trochan- 

 ter ; its distal end is characteristically 

 broad, with little backward extension of 

 the condyles, and a wide intercondylar 

 groove ; the pes is unknown. 



The general facies of this species is 

 not unlike that of certain of the otters, 

 notably JPotamotherium of the European 

 Lower Miocene. The likeness is seen in 

 the low broad occiput, the weak sagittal 

 crest, the broad base of the skull, the 

 probable absence of the alisphenoid 

 canal, the character of the humerus, 

 ulna, radius, femur, and the elongated 

 phalanges, together with probable con- 

 tact between fibula and calcaneum. The 

 character of the lower jaw and teeth, 

 however, precludes the possibility of its 

 being ancestral to this group. The fun- 

 damental differences are seen in the 

 structure of the first molar, which has, 



:% 



Figure 78. — Humerus 

 of Limnocyon xelox Marsli ; 

 front view ; two and one- 

 fourth times natural size. 



80 



79 



Figure 79. — Metacarpal 

 of the pollex of Limnocyon 

 velox Marsh ; front view ; 

 three halves natural size. 



Figure 80.— Phalanx of 

 Limnocyon velox Marsh ; 

 front view ; three halves 

 natural size. 



