218 Mr. J. E. Gray on the Howling Monkeys. 



specimens which we have in the British Museum should be ac- 

 curately described, leaving the consideration of the permanence of 

 the distinctions pointed out to be determined at some future time, 

 or by a person more fortunately placed for such a purpose. In 

 examining the species, I have been induced to believe that the 

 manner in which the hair of the forehead is directed offers 

 perhaps a better character for the separation of the species than 

 that of the colour, or the length, softness or stiffness of the hairs ; 

 I have therefore used it to divide the species or varieties into two 

 groups, though it separates specimens of nearly the same colour 

 and external appearance j and I am aware that sometimes the hair 

 of the forehead has its direction more or less changed by the 

 animal-preserver; yet, as far as I have been able to examine 

 these animals, it appears to afford a very available character. 



The next character in importance appears to be the length and 

 softness, or the stiffness of the hairs of the fur ; unfortunately, 

 the different degrees of this character are not easily expressed in 

 words. In most of the species the hair is of one colour, appear- 

 ing more or less annulated from the slight curl or rather wave in 

 the hair ; but in others it is darker at the base, and one species 

 has an obscure indication of a paler central ring. 



I shall now proceed to characterize the different specimens in 

 the British Museum collection, premising, that for the purpose 

 of coming to a more correct conclusion as to their distinctness, 

 I have examined all the specimens which have come under my 

 observation in other English and continental museums. I may 

 remark that measurements are of little importance, as the adults 

 of all the specimens are nearly of the same size, and as nearly as 

 one can judge from stuffed specimens, the limbs, &c. are nearly 

 of the same proportion. 



I. Forehead high, with the hair reflexed, forming a ridge across 

 the centre of the head, 



1, The Araguata or Brown Howler, Mycetes ur sinus, Pr. Max. 

 Abbild. t. Simiaursina, Humb. Obs. t. 30. S. Guariba, Humb. 

 Obs. Zool. M. fuscus, Kuhl, Beytr. ; Spix, Braz. t. 30. brown 

 var. j M. stramineus, Spix, Braz. t.31. yellow var.; M. barbatus, 

 foem., Spix, Braz. t. 33 ? yellow var. ? 



Brown or blackish, yellow- washed ; hairs rather rigid, brown 

 with yellowish tips. 



Inhab. Brazils and British Guiana. 



We have two males and two females of this species ; one of the 

 latter is young and the other adult. One male is yellow, with 

 the tail, hands and feet, the sides of the head, body and limbs 



