S2 Mr. O, Tlinmas on AitufraJuni Eiiff^ 



Forrest. I have had occasion to exnniine tlie fjencric position 

 ot' the little rat I descrilnd in 1.S89 * as " }fns " orgurus, and, 

 for comparison witli tliat, of all the species hitlierto referred 

 to the group of tlie Jerboa Hats — Conilurus. 



"NVitliout much inquiry into their dental structure, all the 

 Australian long-eared rats were placed hy earlier writers in 

 the genus "Ilapahtis,^^ which was founded by Lichtenstein 

 on the species Jl. oJlipes. The name, however, being pre- 

 occnpied, was rightly supers"ded by J. D. Ogilby, in 1892 fj 

 in favour of that of Conilurus, W. Ogilby, founded on the 

 same well-known sj)ecies. 



In 1808 Mr. "VVaite, of the Sydney Museum, observing the 

 .striking peculiarity of the feet of Conilurus longicaudatus 

 and other allied species, separated off the jerboa-footed forms 

 under the name of Podanomalus, while he gave to another 

 jerboa-footed form, C. cervi'nus, the generic name of Tliyla- 

 comys, which, being preoccupied, he afterwards altered to 

 Ascophari/n.x. 



But in doing so Mr. Waite did not notice that Lesson had 

 already given the name of JVotomj/s to the " Dipus MitchelU" 

 of Ogilby, one of the jerboa-footed species, and therefore 

 Podanomalus becomes a synonym of Notomys. Moreover, 

 as cervinus agrees both in dental and pedal structure with 

 Mitclttlli and longicaudatus, I am not at present ))repared to 

 consider its possession of a gular pouch as a character of 

 generic importance, and should therefore also place Asco- 

 pharynx as a synonym of Notomys. 



But it has not been hitherto noticed that, besides tlie 

 difference in foot-structure that separates Notomys from all 

 the other jerboa rats, there are found in the group two quite 

 different types of molar teeth, the differences being similar to 

 those whicli separate Micromys from Mus^ but even more 

 distinct and sharply defined. 



For while, as shown in Mr. Waiters figures, the species of 

 Notomys and both Conilurus apicalis and murinus have the 

 same number of molar cusps as J/«.s, C. albipes, penicillatus, 

 hirsutus, and certain otlier si)ecies have those described in my 

 " Mus " argurus, i. e. three inner cusps to both m^ and m^, a 

 postero-internal cusp being present which is absent in Mus. 

 This type of tooth was figured in my paper on Mus argurus, 

 and proves to be so constant throughout a number of species 

 that it should clearly be considered as of generic importance. 

 The resemblance of the teeth of Mus argurus to those of 



* Ann. & Mag. Nat. Hist. (0) iii. p. 433 (1889). 

 t Cat. Austr. Mamm. p. 113 (1892). 



