136 SENEGAL PIAPEC. 



of their generic characters is the proportionate length 

 of the lateral toes once alluded to ; it is the in- 

 equality of these toes which indicates that such hirds 

 are arboreal, while those, on the contrary, which have 

 these toes equal, and the middle one lengthened, are 

 of ambulating habits ; or at least that they frequent 

 the ground more than trees. Crypsirma, in this 

 respect, is entirely arboreal, the lateral toes being 

 unequal, and the middle ones short ; while in Pti- 

 lostomus the tarsi are long and robust, the lateral 

 toes equal, and the middle one fully lengthened. 

 In these characters it agrees with all the sub-genera 

 of Corvus, wherein we include the true magpies; 

 but then the whole structure of the bill and nostrils, 

 in our views of the family, decidedly places the 

 present genus, as well as Crypsirina, in a totally 

 different division of it. The only genus of this 

 sub-family ( Glaucopince) which we have not yet 

 seen, is that which should follow Ptilostomus on 

 the other side of the circle, and constitute the 

 tenuirostral type. 



From the circumstance of Le Vaillant having 

 found this species to be migratory in Southern Africa 

 (where it is seen either singly or in small flocks), 

 there can be no doubt that it quits Senegal at certain 

 seasons, along with the grakles herein described, and 

 returns to Western Africa to breed. "We infer this 

 latter circumstance from having seen a young speci- 

 men from Senegal, before it had quite gained its full 

 wing-feathers ; it was much smaller, and the bill was 

 red or flesh-coloured, tipt only with black. We were 



