IjO DR. F. A. JENTINK. MAMMALS. 



so that, were it not that ail thèse spécimens had been collectée! from one and the same 

 locality, there certainly would be sufficient reason to distinguish several sub-species by trino- 

 minals. The same, so to say, endless variation in size and colour in animais belonging to 

 apparently the same species and collected in the same locality is very typical for other 

 New-Guinea-mammals f. i. Phalanger maculatus and Perameles doreyana, as recorded below. 

 I do not venture at ail to give an explication ofthis fact, however I suggest that in this material 

 the lack of enemies perhaps plays an important part. 



Anisomys imitator O. Thomas. 



This large rat lias very peculiar lower incisors; they are so différent from the incisors 

 of ail other rats, that this character alone is sufficient to recognize the species among 

 thousand others; thèse lower incisors combined are of only the same breadth in front as a 

 single upper one, while in depth the lower teeth exceed the upper by a third. The type- 

 specimens are a maie and a female, collected by Meek in British New Guinea, Avéra, Aroa- 

 river; other spécimens hâve never been recorded. Now it is very interesting that there is 

 among a rather large lot of lower jaws belonging to différent Mice and Marsupials, procured 

 January 23, 1910 by the Lorentz-expedition from the indigenous Pesegem-tribe (1500 m.), 

 on the Oroh, a branch of the Lorentz River, a right and left jaw, together forming a com- 

 plète lower jaw of this remarkable species. Therefore we may be sure that this beautiful 

 large rat too must live in the région explored by oui" travellers. This rather large collec- 

 tion of lower jaws — 60 spécimens — ought to hâve a signification, and if it may be allowed 

 to make a hypothesis then I suggest that the Papuans use thèse lower jaws, especially the 

 incisors, as implements, perhaps like the Siriono-Indians do, as described in PETERMANN's 

 Mitteilungen, 191 1, p. 16: „die Siriono-Indianer in Ost-Bolivien haben uberall eigentùmlich 

 geschàftete Nagetierzàhne, die sie als Messer anwenden", and illustrated by Abbildung 3 on 

 Tafel 6. On one of the labels in the collection obtained from the Pesegem-tribe indeed has 

 been remarked: „different lower jaws used for fashioning arrows, collected in the kampong". 



Mallomys Rothschildii O. Thomas. 



Although there are skins nor skulls in the collection made by the Lorentz-expedition, 

 belonging to Mallomys Rothschildii, we may be convinced that this animal is living in rather 

 large quantities in the country round Alkmaar and Pesegem ; indeed I find among the lower- 

 jaw-collection (see Anisomys imitator) 13 right and left halves of lower jaws, belonging at 

 least to 7 individuals ! The size of the jaws combined with the typical structure of the molars 

 leaves no doubt as to the identification. They hâve been procured January 19 10. 



The type-specimen of this large rat is an adult maie in the Tring Muséum; its skull is 

 in the British Muséum ; it has been captured between Mount Musgrave and Scratchley, British 

 New Guinea. In the Leyden Muséum there are three spécimens, collected at the Rawlinson 

 Mountains, Huon Gulf, German New Guinea; so that it may be stated that this species as so 

 many other New Guinean-species lias a very large area of distribution. 



The lower molars of Rothschildii never before having been figured, Plate VII, fig. dw\\\ 

 be not without interest. 





