390 THE PUEECO EPOCH. 



lost in my specimens. The cuboid is robust, and not flat, extending well 

 beyond the navicular. Its distal extremity does not display distinct facets. 



The navicular nuich resembles that of Phenacodus. It is proximally 

 concave; its inferior aspect has three facets, of which the internal is largely 

 posterior. The ectocuneiform has an elongate posterior tuberosity. It has 

 also a proximal facet of the external side which corresponds with one of the 

 na\ncular, for the cuboid. Its distal face is concave. 



Portions of two posterior feet preserved, display five metatarsals, and 

 several phalanges. The distal carina of the former is posterior and weak. 

 The latter are rather narrow for an ungulate, but are not elongate, and are 

 rather depressed ; the distal ones are more robust, and are rather more nar- 

 rowed distally than usual in ungulata, and the neck of a broken ungual 

 phalange of an extei'nal digit is nearly round in section. The third digit is 

 longest, and the first, shortest; it is not very short, and is quite slender. 

 Sesamoid bones are probably present The posterior foot is that of a planti- 

 grade animal. 



I have obtained a cast of the top and sides of the cerebral hemispheres, 

 and the proximal portion of the olfactory lobes, from a skull of a Periptijchus 

 in which the teeth are presei-ved, and prove the species to be the P. rhahdodon. 

 I describe it in detail under that species, but state here that the olfactory lobes 

 are enormous, and the hemispheres small and very fla^. The mesencephalon 

 is entirely exposed. 



The position of this genus and its immediate sXXie?, Anisouchus, Haploco- 

 nus, and Uemithlceus, is not yet positively determined. But three references 

 are possible, viz, to the Taxeopoda Condylarthra, the Bunotheria Creodonta, 

 and the Marsupialia. As no undoubted marsupial characters have been found, 

 discussion of their affinities to that order is deferred. Nevertheless it must 

 be remembered that there are no osteological characters common to all Marsu- 

 pialia, and that the undoubted characteristics of that order can be found in the 

 soft, parts only. The determination of extinct Marsupialia will, on this ac- 

 count, always be difficult. The sculpture of the premolar teeth is not 

 unlike that seen in the fourth premolar of Ptilodus. The character of the 

 condyles of the humerus is, however, totally unlike that of Cutopsalis and 

 Mcniscoessus. The dentition is against reference to the Creodonta. excepting 



