6o4 



MQRID^— EPIMYS 



Remarks : — The following measurements from Hossack (op. at., 9) 

 illustrate the changes of bodily proportions which transpire with 

 growth : — 



Weight : — Two captive male alexandrinus (or frugivorus) weighed 

 4 and 5 ounces, or 113-3 and 141-6 grammes respectively; a female 

 E. r. rattus in captivity weighed 5-25 ounces, or 148-5 grammes 

 (Millais, ii., 208). The weights recorded by Eagle Clarke vary between 

 139-4 and 215-S grammes, but as will be seen from the above table 

 these weights are not those of the largest individuals enumerated. 

 It is, however, improbable that the weight ever much exceeds 300 

 grammes ; full-grown specimens of norvegicus frequently weigh from 

 450 to over 500 grammes. This great difference fully explains the 

 inability of rattus to withstand its rival. 



Skull : — Condylo-basal length, 38 to 45 ; zygomatic breadth, 19-2 

 to 22; interorbital constriction, 5-8 to 6-4; occipital breadth, 15 to 

 17-2; depth of brain-case at middle, 10-8 to 12-6; length of nasals, 

 14 to 17 ; of diastema, 10-2 to 13 ; of mandible, 23-2 to 28; of maxillary 

 tooth-row, 6-4 to 7-4; of mandibular tooth-row, 6-2 to 7-2. 



Distingmsliing characters: — All the sub-species of E. rattus are 

 best distinguished from all forms of norvegicus by their lightness, 

 elegant build, longer tails, and larger and much more delicate cars. 

 The adult skull has larger bullae, and presents well-marked distinctions 

 in the parietal and interparietal regions, as described above. 



Habits : — A general account of the habits of rats is given below 

 under E. norvegicus. The Black Rat is essentially a climber,^ and does 

 not burrow under houses or infest drains like its rival ; it shows no 

 liking for water, which it perhaps only enters occasionally, as when 

 danger presses. As compared with the Brown Rat, it is doubtless in 

 the main a clean feeder — possibly evidence of its more salubrious 

 station rather than of a nicer or daintier palate. Lataste (313) says 

 that it is by no means mute. Observers differ as to its odour, for 

 while de I'lsle (184) describes it as more odorous and fetid than 

 norvegicus, Adams (MS.) states it to be without the offensive smell of 

 the latter species. 



According to Shipley ,2 this species does not breed before it has 



' Hossack describes it as scampering upside down along the cage wires. 

 ^ Joum. Econ. Biol., iii., 1908, 62. 



