Geocirapl ileal Races o/Lufreolina crnssicaudatn. 583 



Dorsal I 6; H times as distant from base of caudal as from 

 end of snout ; spine | length of bead ; first three soft rays 

 subequal, as long as head, reaching adipose fin when laid 

 back. Base of adipose fin nearly twice in its distance 

 from rayed dorsal. Anal 11 ; 8 rays branched. Pectoral 

 spine I length of head, strongly serrated on inner border. 

 Caudal deeply forked, with pointed lobes. Caudal peduncle 

 about 1 J as long as deep. Brownish above, lighter below ; 

 base of rayed dorsal and adipose fin dusky ; anal with a dark 

 patch ; a blackish patch behind gill-cover. 



A single specimen^ 105 mm. in total length_, from Bandama 

 Biver. 



Closely allied to G. tilhoi^ Pellegriu, differing chiefly in 

 the form of the dorsal fin. 



LXII. — The Geographical Races o/Lutreolina crassicaudata. 

 ^ ^y Oldfield Tho.a[as. 



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



The distribution of the South Auierican niiiik-like Opossum, 

 LntreoUna crassicaudatay is a very peculiar one, as tl 

 animal occurs in British Guiana, and then only reappears in 

 Paraguay and Argentina, being completely absent throughout 

 Anicizonia and Brazil. 



Whether the British Guiana form, for which tlie name 

 hirneri is available, should be treated as a separate species 

 from the southern ones, is ratlier doubtful, but after some 

 consideration I am inclined to keep to the opinion expressed 

 in the Catalogue of Marsupials that all the forms of the 

 group may be considered as one species. For the range m 

 size of the southern forms just includes that of tumeric so 

 that tliere is no gap in the measurements, at least of the 

 males, even if there is the great gap in geography. And, 

 again, the southern forms, though presenting well-maiked 

 geographical races, all do, or seem likely to, intergrade, as 

 tiiere are there no geograpliical gaps to make unbridged gaps 

 in the characieis. 



The forms I should recognize may be distinguished as 

 follows : — 



le 



A, Sexes materially diflerent in size, skull-length 

 of $ o.bout So per cent, of that of c? • 

 «. Skull-length of ^ about CO mm.; of $ 52. 



British Guiana \. L. c, tunieri, 



b. Skull-length of ^ about 70 mm. ; of $ 59. [caudata, 



Paraguay 2. L. c. crassi- 



