250 On neio Forms of Saimiri, Oiyzomys, &c. 



breadth across brain-case just behind zygomata 33; palate 

 length 38"5; diastema "25; palatal foramina 8 X 3"2 ; length 

 of upper tooth-row 18'1 ; combined breadth of upper in- 

 cisors 5'2. 



Hah. Yucatan (probably near Izamal). 



Type. Male. B.M. no. 91. 3. 24. 1. Collected by Dr. G. 

 F. Gaumer. 



While all the porcupines of this group are extremely 

 similar externally, the skull-difFerences between individual 

 specimens, even from the same place, are very great, and it 

 is most puzzling to know what should be put down to indi- 

 vidual variation and what to specific or subspecific distinction. 

 But the very small size of this Yucatan skull (a Guatemalan 

 one has the basilar length 8 millim. greater), its smooth even 

 convexity above, the development of the inflated postorbital 

 projections, and the small incisors and cheek-teeth induce me 

 to think tliat this form of C. mexicanus should be distinguished 

 by name. In any other group, having less variable skulls, 

 the differences would be fully specific. 



Cyclopes didactylus eva, subsp. n. 



Size as usual. General colour of body comparatively dark, 

 as in C. d. ida and true didactylus, not yellowish as in G. d. 

 dorsalis. Face, forearms and hands, lower legs and feet 

 strongly yellow, matching these parts in G. d. dorsalis. 

 Shoulders and thighs not greyer than rest of body, but 

 tending towards yellowish. Dorsal streak present, fairly 

 well defined ; sternal streak vague and ill defined, but rather 

 variable in development. Under surface dull buffy, more or 

 less suffused with fulvous ; inner sides of arms and legs dull 

 yellow. Tail yellow, becoming bright golden yellow at its tip. 



Dimensions of the type (measured in the flesh) : — 



Head and body 200 millim.; tail 206; hind foot 31; 

 ear 13. 



Skull: greatest length 50; interorbital breadth 11; breadth 

 of brain-case 23 ; palate length 20. 



Hah, of type. Rio Tapayo, N.W. Ecuador. Other speci- 

 mens from Balzar Mts., W. Ecuador, and Bogota, Colombia. 



Type. Old female. B.M. no. 2. 7. 26. 3. Collected 

 16th November, 1901. 



This form is intermediate between the yellow G. d. dor- 

 salis of Central America and the darker grey-limbed and 

 grey-tailed C. d. ida and didactylus^ having the greyish 

 body of the two latter, with the yellow limbs and tail of the 

 first named. 



