NOTES. 179 



1879. In 1886 DOHRN thought he had proved that the anterior 

 portion of them, which bends upwards on either side of the 

 pharynx and forms the peripharyngeal grooves, represented the 

 last traces of the aborted first pair of gill-clefts. Although they 

 appear at the place which was formerly occupied by these rudi- 

 mentary gill-pouches, yet, according to Dohrn's own account, they 

 do not appear until after the gill-pouches have completely flattened 

 out. Under these circumstances, but above all, in view of the 

 relations of the homologous peripharyngeal bands in Amphioxus 

 which exist both before and after the disappearance of the first 

 pair of gill-clefts (i.e. first primary gill-Cleft and club-shaped 

 gland), it must be assumed that Dohrn's interpretation, though 

 most natural, was nevertheless somewhat at fault. 



