22 Mr. F. E. Beddard on the 



main stem of the feather ; the structure as a whole only 

 differs from that of Perdix in being comparatively smaller 

 and bearing fewer barbs ; I do not at all follow Dr. Roche- 

 brune's distinction between the two families. If the after- 

 shaft be "single" in Perdix it certainly is so also in Nurnida. 

 In the feathers of Cathartes Dr. Eochebrune states the 

 presence of a lai'ge aftershaft, while Nitzsch distinguishes 

 this genus and Pandion from the rest of the Accij)itrin8e 

 Diurnse by the absence of the same structure. In these two 

 genera^ however^ as well as in the Owls, the aftershaft is 

 not entirely unrepresented, but, as Nitzsch correctly says, 

 its place is occupied by a tuft of isolated barbs ; it is easy to 

 separate the individual barbs by means of a needle, and to 

 assure one's self that each springs sepai'atelij from the main 

 stem of the feather; the structure therefore does not fall 

 within Nitzsch's definition of an aftershaft. This difference, 

 which Nitzsch has pointed out between the Accipitrinse 

 Nocturnse on the one hand and the Accipitrinse Diurnse, with 

 the exception of the two genera Cathartes and Pandion, on 

 the other, is perfectly plain. Dr. Rochebrune's definition of 

 an aftershaft, however, does include this tuft of barbs ; the 

 aftershaft, according to him, is occasionally ' sessile ' upon 

 the feathershaft, and is not always borne upon a secondary 

 shaft ; the feathers of Cathartes and Bubo maculosus are 

 furnished with an aftershaft of this kind, which is no doubt 

 the equivalent of the ' true ' aftershaft of the Accipitrinae 

 Diurnse. Dr. Rochebrune is perhaps, strictly speaking, 

 right in saying that the Accipitriuse Nocturnse are not 

 devoid of an aftershaft ; but he seems to have over- 

 looked that Nitzsch himself had previously noticed this same 

 structure, which he describes as occurring in the place of 

 the aftershaft. Dr. Rochebrune has therefore not pointed 

 out a new fact, but has merely recapitulated what Nitzsch 

 said many years previously, failing, however, to emphasize 

 the essential difference between the ' true ' aftershaft of the 

 Accipitrinee Diurnae and the tuft of isolated barbs which 

 characterize the feathers of Cathartes and the Accipitrinae 

 Nocturiiae, 



