678 ^Jr. O. Thomas on I lie Bandicools of 



dirter tVoiii tlio maiiilanJ Bandicoot, and on compari.son 1 find 

 the difference so marked and so constant as to be wortliy o£ 

 vecofrnition by name. In examininf^ the skulls I have bad 

 for comparison tiie fine series of Isoodon obesulus obtained 

 by Mr. Shortridi^e in South-west Australia, a series numbering 

 nine males aiul five females, ami showing well the age and 

 sex characters found in this difficult genus. 

 The island-form I would propose to call 



Isoodon nauticuSf sp. n. 



Size markedly smaller than in the continental ohesuhis, the 

 skull of an adult male only about 55 mm. in length, as 

 compared with 70 or more in obesulus. General colour com- 

 paratively pale; under surface white; hands and feet with 

 grey-brown metapodials and white digits ; tail brown above, 

 whitish below. 



Skull far smaller than in obesulus, smooth, and almost with- 

 out cranial ridges, the sagittal crest obsolete, and even the 

 two lateral thickenings of the occipital much less developed 

 than usual. Nasals much shorter and narrower than in 

 obesula. Bullasnot far from as broad as in obesuhi, but pecu- 

 liarly shortened, rather abruptly cut off behind. 



Teeth small throughout. Tlie three juxtaposed incisors, 

 P-i*, together about 3 mm., as compared with 4'5 and 

 upwards in obesulus. Canines short. Secator and molars 

 all proportionately reduced. 



Dimensions of the type (measured on the spirit-specimen 

 before skinning) : — 



Head and body 242 mm.; tail (damaged, 103 mm. in 

 another rather younger specimen); hind foot 50. 



Skull: greatest length 54*5; condylo-basal length 53; 

 zygomatic breadth 25 3; nasals 21*7 x5"2; intertemporal 

 breadth 11"6 ; palatal l»^ngth 31 ; oblique diameter of bulla 

 10'3 ; dental length 98 ; front of canine to back of 7U* 20*5 ; 

 diameter of secator 2 ; combined length of m^"' 8"5. 



Hub. Franklin's Island, Nuyts Archipelago, S. Australia. 



Type. M\\\i m^\Q. B.M. no. 22. 4. 15. 6. Collected and 

 presented by Prof. F. AVood Jones. 



The main difference of this island Bandicoot from /. obesulus 

 is its markedly smaller size, as compared with continental 

 specimens of corresponding sex. Its bullae are also shorter, 

 and it is probable, as occurs with other insular forms of the 

 genus, that there is less sexual difference in size than in 

 the mainland animal. 



