476 ANATOMY OF THE CRESTED RAT CHAP. 



Sub-Fam. 6. Dendromyinae. The genus Deomys is an Afri- 

 can form, consisting of only one species from the Congo region. 

 D. ferrugineus has a reddish colour as its name implies ; the soles 

 are quite naked and the tail is long and slender. It is con- 

 siderably longer than the body, measuring (minus a fragment of 

 the tip) 172 mm., while the body is 125 mm. long. The 

 characters of the molar teeth, which are three, are intermediate 

 in their form between those of the true Rats and those of the 

 Hamsters. 



Dendromys is also Ethiopian in range. There are several 

 species. D. mesoinelas is a smallish creature, 60 mm. long, with 

 a tail of 90 mm. 



Steatomys is another African genus, allied to the last. Its 

 tail, however, is only half the length of the body. The two 

 remaining genera are Malacothrix and Limacomys. Their range is 

 African. 



Sub-Fam. 7. Lophiomyinae. Allied to the Hamsters is the 

 singular East African genus Lophiomys, with only one species, 

 L. imliausi, of Milne-Edwards. 1 The size is between that of a 

 Rabbit and of a Guinea-pig. The stomach is curved and somewhat 

 intestiniform. It has been termed the Crested Rat on account of 

 the " prominent crest of stiff hair running down the back." The 

 fingers and toes are five, and the very long tail is clad with hair 

 longer than that upon the body generally. The pollex is rudi- 

 mentary, and the hallux is opposable. 



The most remarkable structural feature in this genus con- 

 cerns the skull, and on account of this it has been regarded as 

 the type of a separate family. The temporal fossa behind the 

 eye is covered over by a complete bony plate, formed by a down- 

 growth of the parietal, meeting an upgrowth from the malar ; 

 this singular arrangement of the bones recalls the conditions 

 which obtain in turtles. The whole skull, moreover, is covered 

 with symmetrically disposed granulations, such as are found in 

 no other mammal ; it suggests rather the skull of certain fish. 

 It is believed that the bony plate already referred to is not really 

 a portion of the bones of which it appears to be a prolongation, 

 but merely an ossification of fasciae in this region. The atlas 

 is granulated like the skull ; there are sixteen pairs of ribs and 

 a feeble clavicle. The molars are three, and of a peculiar form. 

 Nouv. Arch. Mus. iii. 1867, p. 81. 



