(72) 

 512 0. GORDON HEWITT. 



the position of the pharyngeal skeleton, to the whole of which 

 the name " cephalo-pharyngeal skeleton " has been given. All 

 that now is left of the cephalic segment consists of a pair of 

 oral lobes, whose homology with the maxillae is very proble- 

 matical, and at present is not safely tenable. On the dorsal 

 side the oral lobes are united posteriorly. Each bears two 

 conical sensory tubercles (o. t.), which are situated, the one 

 dorsally, and the other anterior to this and almost at the apex 

 of the oral lobe. The ventral and ventro-lateral surfaces of 

 the oral lobes are traversed by a number of channels, which 

 will be described later. 



The post-cephalic segment, which is composed of the first 

 and second post-oral segments and represents the second and 

 third segments of the body, is conical in shape. The first 

 post-oral segment (ii), to which Lowne gave the name 

 "Newport's segment," is limited posteriorly by a definite 

 constriction and is covered with minute spines. The second 

 post-oral segment bears laterally at its posterior border the 

 anterior spiracular processes (a. sp.) The remaining seg- 

 ments of the body four to twelve are on the whole similar 

 in shape. At the anterior edge of the ventral side of each of 

 the sixth to twelfth body- segments there is a crescentic pad 

 (fig. 5, sp.) bearing minute and recurved spines; these are 

 locomotory pads by means of which the larva moves forwards 

 and backwards. It is important to note that these pads are 

 situated on the anterior border of the ventral side of each 

 segment as they do not appear to have been carefully placed 

 in the previous figures of this species. In addition to these 

 spiniferous pads there are two additional pads of a similar 

 nature, one on the posterior border of the ventral side of the 

 twelfth body-segment, and the other posterior to the anus. 



The terminal or thirteenth body-segment is obliquely trun- 

 cate, but the truncate surface, which occupies more than half 

 the posterior end of the larva, is not very concave as in the 

 blow-fly larva. It bears in the centre the two posterior 

 spiracles (fig. 3, p. sp.), which are described in detail with the 

 tracheal system. On the ventral side of the terminal segment 



