530 Mr. 0. Thomas on 



cells; per., peritoneura ; p^r.c, pyramidal cells; s.c, sensory cells; 

 s.il.ff., spermidncal gland (prostate); sep., SBptum 7/8; sept, and 

 se;ji^.?)i., septal membrane; s./., secondary fnniiel ; s./.', seta-follicle ; sh., 

 connective-tissue sheath round the dorsal vessel ; s.o., spermathecal 

 opening; sp.b., sperm-blasts; sp.c, spherical cells; sj}.d., speriuiduct; 

 sjj.m., sperm-monila ; sp.s., sperm-sac ; sl.l., shorter twisted lobe ; t.h., 

 tigroid bodies ; tc, testis-cells ; v., vesicle ; y.c, j'olk-cells ; y.sp., yolk- 

 p'atelets. 



LI. — Notes on the Species o/Notomys, the Australian 

 Jerhoa-ra's. By Oldfield Thomas. 



(rublished by permission of the Trustees of the British Museum.) 



The intevosthig jerboa-rats forming tlie gcjiius ]S^otomi/s have 

 long been in a state of considerable confusion as regards the 

 species that exist, or, rather, have existed; for it is to be 

 feared that few of them still survive, exce})t in the centre 

 and north of the continent. 



When Central Australia was being explored under the 

 direction of Prcf. Baldwin Spencer, a ceriain number of 

 specimens were obtained, and Mr. Waite published some 

 valuable notes on these*. He formed on them the groups 

 Podanomahis and ThyJacomys (which he afterwards renamed 

 Ascopharynx) ; but, as I have elsewhere f shown, these luimes 

 should be merged in the earlier Notomys of L?ss!)n. 



The throat-pouch described by Mr. Waite iipp;^ars to be 

 present in most if not all of the species, and would seem to 

 be a skin-gland, such as many rodents, bats, and marsupials 

 possess in a similar situation. Its use is probably of a 

 sexually attractive nature, and I cannot at all accept the 

 suggestion of J\Ir. Waite that the pouch might be of use for 

 storing food, as is the case with the American Geomyidaiand 

 the European Hamsters. Its structure and general aj)pearance 

 seem to me to preclude any such possibility. 



The two main causes of the confusion that exists as to the 

 S[)ecies are, firstly, the publication by Gray of several names 

 without descriptions, and, secondly, the fact that Gould, who 

 had an excellent hunter's knowledge of the forms dealt with, 

 knew nothing and gave no descriptions of the skulls, by 

 which alone the species can be satisfactorily determined. 



The following notes are based on a study of the series in 

 the British Museutn, which contains specimens obtained by 



* P. Koy. Soc. Victoria, (2) x. pt. ii. p. 117 (1898). 

 t Ann. & Mag. Nat. Hist. (7) xvii. p. 83 (1906). 



