272 CLASS MAMMALrA. 



The claws are nearly of an equal length, though the 

 middle one is rather the longest; they are very strong both 

 on the hind and fore-feet, but especially on the latter. 

 There is a small external ear concealed under the hair. 



The Ai is said to be about as big as a Cat, but it va- 

 ries considerably in size ; its head is a little more than 

 three inches in length ; its body about fourteen ; its tail 

 eleven lines ; the arm eleven inches ; and the leg six only; 

 the claws of the fore-feet, when measured underneath, and 

 in a right line, or, mathematically speaking, taking the chord 

 between their base and extremity, are thus : the middle one 

 two inches six lines, and the two external ones two inches 

 three lines ; on the hind-feet, the external claw measures 

 one inch six lines ; the middle, two inches and one line, and 

 the internal, one inch nine lines. 



The Ai has not, at all times, the mark on the shoulders 

 of which we spoke above, and many individuals are to be 

 found without it. Sonnini even asserts that the Ai a dos 

 brule (a name which he gives to that one which has 

 the orange spot and the black line) is more rare at Cayenne 

 than the other variety, which he considers as that which 

 properly constitutes the species Ai. One variety of this 

 species has the fur generally gray, the throat being covered 

 with a short and brown hair ; it has a yellowish band over 

 the forehead, and which also extends across the cheeks; 

 the hairs of the head do not diverge from a common centre, 

 but are directed right and left, on each side of the neck ; 

 it has also the aforementioned spot between the shoul- 

 ders. 



There is another with a brown throat, but without the 

 spot on the shoulders ; it belongs to Brazil. 



It is not yet ascertained whether these different varieties 

 may not constitute so many distinct species. Against the 

 multiplication of species we have too often declared our- 

 selves, to incline to the affirmative of such a question with- 



