THE AGUARA WOLVES. 245 



vertical opening, but liable to assume tlie rounded 

 shape in a moment ; and this eflPect being generally 

 produced under all circumstances of emotion or par- 

 tial obscurity, in all the nocturnal, the criterion 

 escapes notice, unless it be determined by dissec- 

 tion, an operation demanding manual skill and pre- 

 vious anatomical education; these requisites not 

 being always possessed by travelling investigators, 

 leave doubts which can be removed only by such 

 establishments as zoological gardens, where species 

 can be studied living and be dissected after death. 



South America, when first discovered by the 

 Spaniards, was possessed of canines absolutely indi- 

 genous, some universally wild and others liable to 

 be partially reclaimed ; all more nocturnal than the 

 former dogs and less so than true foxes. Of the 

 first -class there is perhaps only the Chrysocyon 

 before described; in the second, although clearly 

 distinguishable into two groups, alike furnished 

 with rounded foreheads, there are general indica- 

 tions of a more placable nature. The eyes of some 

 are considered circular; they have comparatively 

 longer and bulkier bodies and shorter tails, while 

 the others with the external form of foxes, the nose 

 still more pointed and brushes even longer and 

 more ample than these animals, have indeed the 

 pupils of the eyes vertically contractile, but so im 

 perfectly, that they become elliptical only when the 

 head is forcibly held against a strong light; they 

 are hence crepuscular, not nocturnal, unless there 

 be a clear moonlight. Their propensities to rapine 



