On small Mammals from North-western Patagonia, 199 
belonged to a very different group—the Opisthomi (cf. 
Regan *)—and I think that Chaudhuria may be characterized 
simply as a Mastacembelus without spines and without rostral 
appendage. In other characters—torm, scaling, structure 
and position of fins, nostrils, mouth, lips, dentition, gill- 
openings, branchiostegal rays, ete.—there seems to be no 
difference between the two genera. The few details given of 
the skeleton of the head of Chaudhuria are applicable to 
Mastacembelus, allowance being made for the preemaxillary, 
with the attached maxillary, being described by Dr. Annandale 
as the maxillary only. The peculiarities of the vertebra, to 
which Dr. Annandale has called attention, are found in 
Alastacembelus also. 
Dr. Annandale informs me that he has no time at present 
to make a further investigation in order to test the validity 
of my opinion as to the systematic position of Chaudhuria, 
and, as no specimens are available for examination in this 
country, it seems worth while to publish this note. 
‘ 
XVI.—On small Mammals collected by Sr. FE. Budin in 
North-western Patagonia. By OLDFIELD ‘l'HOMAS. 
(Published by permission of the Trustees of the British Museum.) 
SENOR EK. BupIn, the collector of the Chumbicha mammals 
described in the last number of the ‘Annals’ +, helped by 
the kindness of Dr. O’?Connor, Mr. Charles Lockwood, and 
the authorities of the Argentine Southern Land Company 
of Buenos Ayres, has also been enabled to make a collecting- 
trip to Lake Nahuel Huapi, in the mountainous part of 
North-western Patagonia, and to two other places in the 
same region, Pilcafieu on the Upper Rio Negro (41° S., 
71° W.) and Maiten on the Upper Chubut (42°8., 71° W.). 
At each of these places he made a collection of small 
mammals, mostly Muridee and tuco-tucos, and all prove to be 
of the greatest interest. 
Of the twenty forms obtained | have found it necessary to 
describe nine as new, while he has also collected an animal— 
the Recthrodon longicaudatus of Philippi—which proves to 
represent a very distinct new genus, quite unlike anything 
previously known to me. 
* Regan, “The Ostevlogy of the Teleostean Fishes of the Order 
Opisthomi,” Ann, & Mag. Nat, Hist, (8).ix. 1912, pp. 217-219, 
+ Supra, p. 115, 
14* 
