THE ACTIVE GIBBON. 153 



several times, until sufficient impetus is gaineu, and 

 they then dart off with the utmost apparent ease and 

 grace. 



In a state of domestication, they are not so lively as 

 many other monkeys, though susceptible of some cul- 

 tivation; they are easily frightened, and as easily 

 again reassured, fond of ,?eing caressed, inquisitive and 

 familiar, and sometimes playful. In the internal 

 anatomy, they differ from the preceding species in 

 the absence of the guttural sack ; nevertheless, the 

 cry is nearly similar, which must show that this 

 formation is not necessary to produce the howl of this 

 and some other monkeys, or that soma M;her structure 

 mast fill up the deficiency. 



We have now mentioned all the known species of 

 long-armed apes or Gibbons, and there are two forms 

 which by most zoologists have been placed immediately 

 following them, of which we have been unable to see 

 specimens. We shall therefore shortly notice them 

 from the works of highest reputation, before proceed- 

 ing to the Guenons or long-tailed monkeys of the 

 Old World. The first has been characterised by Esch- 

 sholtz, under the name of Prebytis;* possesses no 

 cheek-pouches; has naked callosities; the arms reach 

 to the knees, and the tail is of considerable length. 

 The facial angle 60. Only one species has been 

 discovered in Sumatra, P. mitrula, or capped mon- 



* Ilpfrdt, an old -woman. So called from the resemblance of 

 wi old woman with a cap. 



