252 Bulletin Americon Museum of Natural History. [Vol. XXXIV, 
Mesosciurus chapmani tobagensis (Osgood). 
Sciurus tobagensis Oscoon, Field Mus. Nat. Hist., Zodl., X, No. 4, p. 27, Oct. 20, 
1910. 
Type locality.— Island of Tobago, B. W. I. 
Geographic distribution. Island of Tobago, B. W. I. 
Description.— Slightly smaller than M. chapmani but practically 
indistinguishable in color; there is a tendency to a little more black on the 
tip of the tail, but this proves an inconstant feature, 3 out of 9 Trinidad 
specimens having the tail tip as black as the Tobago specimens, while the 
majority of the Paria Peninsula specimens have the tail tip as black as any 
of the 5 specimens (type and topotypes) from Tobago; some have more 
black and others no distinct darkening of the tail tip. 
Total length, 330; head and body, 165; tail vertebrae, 165; hind foot 
(c. u.), 45”; measurements of the type, an immature female, as given by 
the author from the dry skin. Four topotypes are without flesh measure- 
ments. ‘The hind foot (c. u.), in the skin of the type and 4 topotypes, 
measures 44 (42-45), or about 2 mm. less than in chapmani. 
The total length of the skull cannot be given, the type and topotype 
skulls all lacking the occipital region. The available measurements of 4 
adult skulls are as follows: zygomatic breadth (2 skulls only), 28 (27.5- 
28.5); interorbital breadth (4 skulls), 15.3 (15-15.5), breadth of braincase, 
21.7 (21-22); length of nasals, 14.1 (14-14.3); diastema, 11.3 (11.2-11.5) 
maxillary toothrow (2 skulls), 8, 8. 
Specimens examined, 7—Island of Tobago, B. W. I.: 2, type and 
paratype (Field Mus.); 3, Nat. Mus.; 2, Br. Mus. 
Remarks.— The original description states: “The heavy black tip of 
the tail is the principal character distinguishing this form [tobagensis| from 
S. chapman” (Osgood, |. c.). The type is a young female in full, fresh 
pelage, and is rather more richly colored than any of the four topotypes in 
the National Museum, now before me, especially in respect to the ventral 
surface. 
The main basis for the recognition of this form is its insular habitat and 
slightly smaller size as compared with the Trinidad and mainland representa- 
tives of the species, rather than the darkening of the tip of the tail, which is 
an inconstant character, especially prevalent in the Paria Peninsula series. 
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