SUB-FAMILY MYOXINAE. 



Molars j^, rooted unequal. Post-orbital process wanting. No coecum. Tail variable ; hairy. Ante-orbital foramen 

 situated in the anterior base of the zygomatic arch, small, rounded. 



I have introduced a short notice of the Myoxinae for the purpose of completing the history 

 of the Sciuridae, although no species are known as inhabiting North America. They have 

 quite a general resemblance to the squirrels, but differ in many important points, in fact some 

 authors place them among the Muridae. 



The incisors are laterally compressed ; the molars unequal in size, with the crowns not simply 

 tubercular but complicated ; the series on each side are widely separated and parallel. 



There is no -post-orbital process in the present sub-family, so conspicuous in the Sciurinae. 

 The zygomatic process of the maxillary consists of a broad thin plate extending from the plane 

 of the palate to the upper surface of the skull ; this has a moderately large ante-orbital foramen. 

 Incisive foramina partly in the maxillary, partly in the intermaxillary ; palatine process of the 

 maxillary terminating opposite the penultimate molar, followed by a narrow palatine process 

 of the palatine bone. The interparietal bone is much extended transversely, so as to reach 

 the temporal bones on either side, instead, as in the squirrels, of not extending beyond the 

 parietals. 



Lower jaw with the branches more diverging than in the squirrels ; the descending ramus 

 forming a quadrate process, which is sometimes perforated. The lower posterior angle of this 

 process is incurved, and either angular or rounded. The upper posterior angle is acute and 

 twisted outwards. 



The anterior small molar of the squirrels is wanting ; the crowns are traversed by transverse 

 ridges ; the teeth varying with the genera, from a quite simple structure to a very complicated 

 one. 



The intestinal canal differs from that of all other rodents in having no coecum. The gall 

 bladder is present. 



The form of the skull in some respects approximates to that of the Dipodinae. 



The genera of this sub-family are Graphiurus, Eliomys, Glis, and Muscardinus all belonging 

 to Europe, Central Asia, and Africa. 



A species of Nyoxus was described many years ago by Keich, 1 under the name of M. virginicus j 

 and said to have been brought alive from somewhere near the base of the Blue Mountains of 

 Virginia. The animal was about as large as the house mouse ; the body measuring 3 inches, the 

 tail 1. The tail was hairy and tufted at the tip ; the body reddish brown, paler beneath. 

 The figure appears to represent a true Myoxus, and certainly differs from any animal now 

 known to inhabit the United States. It is, however, not impossible that such a species may exist 

 within our limits, and have hitherto escaped detection, although this is not very probable. 



1 Reich, Beschreibung einer neuer Art von Schlafer; Mag. Gesellschaft Naturf. Frcunde, zu Berlin, 1810, 243; tab. viii. 



