158 ALLEN'S NATURALIST'S LIBRARY. 



IV. THE RED-BACKED TITI. CHRYSOTHRIX CERSTFDI. 



Saimaris sciurea ? (nee Linn.), Sclater, P. Z. S., 1856, p. 139. 

 Chrysothrix sriurea (nee Linn.),Scl., N. H. Rev., 1861, p. 510; 



Frantz. Arch. f. Naturg., xxxv. (i), p. 260. 

 Chrysothrix cerstedi, Reinh. Vidensk. Medd. Nat. For. 



Kjobenh., p. 157, pi. iii. (1872) ; Alston, in Godm. et 



Salv., Biol. Centr. Am. Mamm., p. 16, pi. ii. (1879). 

 Saimiris entomophaga, Sclater, P. Z. S., 1872, p. 3 (nee 



d'Orb.). 

 Saimiri crsfedii, Schl., Mus. Pays Bas, vii., p. 245 (1876). 



Characters. Differs from C. sciurea in having the top of the 

 head black, the back and sides shining red, and the limbs 

 olive. 



Distribution. Panama, Guatemala, Costa Rica, especially their 

 hotter districts, being particularly abundant in the Valley 

 of Terraba and on the plain of Piris. 



THE TITI MONKEYS. GENUS CALLITHR1X. 

 Callithrix, Geoffr., Ann. Mus., xix., p. 112 (1812). 



This genus is intermediate between the Squirrel-Monkeys 

 and the typical Night-Monkeys. In the Titis, sometimes 

 known by the name also of Whaiapu-Sai Monkeys, the fur is 

 sott, the head small, depressed, and not produced backward 

 as in Chrysothrix ; the tail is long and bushy ; the eyes are 

 small, and the orbits intermediate in size between those of the 

 last and the next genus ; the nasal partition is broad, and the 

 ears large. The canine teeth are small, and the angle of the 

 lower jaw expanded, somewhat as in the Howlers (Mycetes}, 

 though to a less extent. 



