272 On some of the Larger Species of Geomys. 
expanded anteriorly, but converging very rapidly posteriorly ; 
ascending processes of premaxille surpassing the nasals 
behind by about a quarter of an inch, the space between their 
posterior ends, behind the nasals, broader than they are. 
Interorbital region very much contracted, considerably 
narrower than the muzzle, its edges rounded, neither ridged 
nor inflated. 
Anterior face of incisors orange-yellow ; their single groove 
narrow and shallow, less developed than in any other species, 
its position decidedly inward of the middle line, the inner 
portion of the tooth being only 43 per cent. of the whole; 
front face of the inner portion very faintly flattened as com- 
pared to the evenly convex outer portion. Molars propor- 
tionally much smaller than in G. grandis. 
Dimensions of the type skin (B.M. 70. 6. 20. 2) :— 
Head and body 295 millim., tail 95, hind foot without 
claws 41 *, length of longest front claw (much worn) 15. 
Skull (see below). 
Hab. 8S. Mexico. Coll. A. Boucard. 
The specimen on which this species is founded is that 
referred to by Mr. Alston t under ‘ Mexico (Geale; Mus. 
Brit.),and came from the same source and probably the same 
place as the type of Oryzomys fulgens, Thos.} 
I have named this handsome animal in honour of Dr. C. Hart 
Merriam, to whose energy and scientific enthusiasm the recent 
enormous increase in our knowledge of North-American 
mammals is mainly due. 
G. Merriam? is readily distinguishable from G. mexicanus, 
of which Dr. Matschie has kindly sent me the original 
measurements, by its much larger size and by the internal 
position of its incisor groove. ‘The latter character will also 
separate Dr. Merriam’s own G. gymnurus, which has, like 
G. mexicanus, its “upper incisors with a single median 
furrow.” 
* With claws 47:5; the claws are, however, much worn and, as usual, 
but little value can be attached to the “ with claw” measurement, at least 
as compared to the far more exact and reliable one without claws. 
This latter has not, I believe, been much used in America, but the 
majority of the Old World zoologists are gradually taking to it, and no 
one who has once tried it, and found its simplicity, convenience, and 
exactitude, would return to the loose and old-fashioned way of including 
the claws, which act as a second variable factor in the most important 
external measurement that can be given of a mammal. 
+ Op. cit. p. 159. 
t Ann. & Mag. Nat. Hist. (6) xi. p. 403. 
