390 My. O. Tliomas on 



The Lutra platensis Group. 

 The difficulties presented by the members of tliis Soutli- 

 American group of otters were the chief reason for the incom- 

 plete state of the 1889 paper above quoted, and but little 

 progress has been made in their elucidation to the present 

 date. 



The only two points that have been published about them 

 are that Nehring * has shown the earliest name, paranensis, 

 Rengger, to have been based on the large Pteronura hrasili- 

 ensis, so as to remove that name from the group, and that 

 Dr. Major has described the Central-American form as a 

 distinct species, L. annectens. 



Material has, however, been gradually accumulating, and 

 I am now in a position to sort this ditficult group into seven 

 fairly distinct forms, of which the characters and distribution 

 are as follows : — 



1. Lutra annectens J IMaj. 



Ann. & Mag. Nat. Hist. (6) xix. p. 618 (1897) ; Zool. Anz. 1897, 

 pp. 136-142. 



Nose-pad quite naked, its upper line of demarcation with 

 a distinct upward projection in the centre, as in the European 

 otter, L. lutra. 



Skull very broad and low, with broad flattened brain-case 

 and widely expanded mastoid processes. Nasal opening 

 fairly narrow, its breadth less than its slanting internal 

 height-length diameter. Bullae well swollen. 



Upper carnassial not very large, the hinder edge of its 

 inner lobe not touching the front of m^. 



A male skull measures in condylo-basal length 117 mm. ; 

 zygomatic breadth 80 ; mastoid breadth 78 ; antero-posterior 

 diameter oi p* 10*2. 



Hah. Central America : Tepic, Jalisco, Mexico {Buller) ; 

 Guatemala (Sahin). 



Txji^e in British Museum, no. 92. 3. 17. 8. 



2. Lutra emerita, sp. n. 



Nose-pad as in annectens. 



Size rather less than in that species. Skull with com- 

 paratively large, rounded, and high brain-case, tlie height 

 greater and the breadth less than in the Central-American 

 species. Upper profile convex. Sagittal crest little developed ; 



* SE, Ges. uat. Freund. Berl. 1900, p. 221. 



