398 ME. OLDFIELD THOMAS ON MAMMALS 



collected by Mr. Charles Hose, I have carefully compared with Rhynchomys, and have 

 come to the conclusion that, in spite of the absence of any tendency towards a 

 reduction in the dentition, there is a genuine relationship between the two forms. 

 In the Celebean animal the general shape of the skull is very similar to that 

 found in Rhynchomys: the peculiar anterior nasal bulging is present; the brain- 

 case is similarly smooth and rounded ; the supraorbital and temporal ridges, 

 although present, are very small ; the zygomatic root is slightly slanted back ; and the 

 posterior palatal region is strikingly similar to that of Rhynchomys both in the breadth 

 and shape, of the posterior nares, and the entire suppression of the external pterygoids. 

 The incisors again — or at least the upper ones 1 — in size, proportions, and position are 

 more like those of Rhynchomys than of ordinary murines. 



On the other hand, the molars of Echiothrix are absolutely murine, and show no 

 trace of reduction or any other peculiarity. The third molar is, of course, present 

 above and below, and is of full murine proportions. 



On the whole it seems probable that we have in Echiothrix a form which bears to 

 Rhynchomys very much the relation that Crunomys does to Hydromys, being, as in that 

 case, the first commencement of a line of modification which culminates in a genus 

 sufficiently distinct to demand subfamily separation from the main trunk of the 

 Murinse. If this be true, it would then probably be best to include all the members 

 of the diverging branch within the special subfamily, even if nearer to the trunk than 

 to the extremity, and I would therefore suggest, as in the case of Crunomys, that 

 Echiothrix should be transferred to the Ehynchomyinse, a name which would be 

 particularly suitable owing to the long snout being the most obvious character that 

 the two genera have in common. 



It is, of course, just possible that when unworn teeth of Rhynchomys are examined 

 they will show a structure quite incompatible with the view that this form is related to 

 Echiothrix, but it seems to me that the many cranial characters which the two forms 

 have in common render this possibility very unlikely. 



KiiTNCHOMYS soricoides Thos. (Plate XXXI. fig. 2.) 



Size of a common Eat. Fur thick, close, and velvety, about 14 or 15 millim. long on 

 the back. General colour dark olivaceous grey, becoming more yellowish in old age. 

 Under surface dirty grey, not sharply defined, but becoming lighter and more sharply 

 defined in old examples ; a white patch sometimes present on the throat or chest. 



1 The lower incisors of Echiothrix are perfectly unique in being widely separated from each other terminally, 

 so that, being also very long, their tips bite up on each side of the upper incisors, -which project down between 

 them. How far up they actually go in life on the sides of the muzzle cannot be determined without 

 the examination of fresh or spirit specimens, but their splay is sufficient for the whole muzzle to close down 

 between them. 



