NO. 22 MAMMALS FROM PANAMA AND MEXICO — GOLDMAN 7 



NECTOMYS ALFARI EFFICAX, new subspecies 



Type from Cana (altitude 1,800 feet), Eastern Panama. No. 

 178627, male adult, U. S. National Museum (Biological Survey Col- 

 lection), collected by E. A. Goldman, March 12, K)i2. Original 

 number 21498. 



General characters. — Closely allied to Nectomys alfari alfari ( Sig- 

 modontomys alfari Allen) ; general color of upper parts richer, more 

 tawny ochraceous ; skull with narrow braincase and massive ros- 

 trum. Somewhat similar to A r . esmeraldarnm, but larger; color 

 decidedly paler, more ochraceous ; skull more elongated. 



Color. — Upper parts rather pale tawny ochraceous mixed with 

 black, the ochraceous predominating especially on cheeks, shoulders, 

 flanks and outer sides of hind limbs ; top of head and face darkened 

 by more abundant admixture of black-tipped hairs ; under parts dull 

 white, usually more or less distinctly washed with pale buff ; feet 

 flesh colored, thinly clothed with short grayish hairs ; tail brownish 

 above and below. 



Skull. — Similar in general to that of N. a. alfari. but braincase 

 narrower ; rostrum more massive ; nasals shorter and broader pos- 

 teriorly ; frontal region narrower, but with similarly developed 

 supraorbital and temporal ridges ; interparietal smaller ; interptery- 

 goid fossa narrower ; maxillary toothrow shorter. Contrasted with 

 that of N. esmeraldarnm the skull is relatively narrower and more 

 elongated, the rostrum and frontal region being decidedly longer. 



Measurements. — Type: Total length, 305 millimeters; tail verte- 

 brae, 179; hind foot, 36.5. Average of five adult topotypes: 314 

 (304-320); 178 (168-196) ; 36.1 (35.5-37). Skull (type): Greatest 

 length, 36.2; condylobasal length, 27,.8\ zygomatic" breadth, 19.7; 

 nasals, 14.2; interorbital breadth. /.2\ interparietal, 8.2 x ^.2; 

 incisive foramina, 5.5 ; length of palatal bridge, 8.5 ; maxillary tooth- 

 row, 5.4. 



Ronarks. — This form seems to be more closely allied to the species 

 described as Sigmodontomys alfari than to any of the small Smith 

 American members of the genus Nectomys. It may be not very 

 unlike N. russiiliis Thomas, from Valdivia, Colombia, specimens of 

 which I have not seen, but judging from the description the latter 

 is darker in general color, with less contrast between upper and 

 under parts. 



Specimens examined. — Total number, 2^,. all from the type locality. 



