96 



S. EADWEN AND A. E. CAMERON. 



margins of segments 3 to 10 armed with narrow, elongate, sharp-pointed, denticular 

 scales interspersed with similar smaller ones ; base of scale brownish yellow, apices 

 and margins black and more strongly chitinised ; the larger scales apparently 

 strengthened by a median rib. Segments 11 and 12 unarmed. Posterior pair 

 of spiracles scarcely projecting beyond the extremity of the body, sessile (fig. 7). 



Raillet (8), on page 758, and Neumann (9), on page 345, state that in the recently 

 emerged larva of G. nasalis there is but one row of spines on the anterior border of 

 the segments. With this opinion we do not agree, as examination of a large number 

 of specimens shows that the spines or scales — as we prefer to call them — arise from 

 the posterior margins, and further, their arrangement is somewhat irregular, so that 

 they do not assuredly form a single well-defined row. 



Gastrophihis haemorrhoidalis. 



Number of segments, 13 ; hairless. Length, - 585 mm. ; greatest width, 0133 mm. 

 General colour translucent white, with the exception of the brownish-black of the 

 denticles and scales of the segmental armature. General shape fusiform, tapering 

 to both extremities. Single pair of mouth-stylets (mandibles) directed anteriorly. 

 Strongly developed crown of elongate, slender, recurving head-hooks arising from the 

 anterior margin of segment 2 with numerous smaller placoid denticles and toothed 



lami 



Fig. 8. Larva of Gastrophihis haemorrhoidalis, X 140. 



scales intermingled and irregularly arranged in a row. Segments 11, 12 and 13 

 devoid of armature. . Ultimate segment bearing posteriorly two cylindrical processes, 

 at the extremity of each of which is a spiracle where the main tracheal trunk of each 

 side terminates, as is the case in the larvae of G. intestinalis. The armature not so 

 strongly developed as in the larvae of G. intestinalis and G. nasalis (fig. 8). 



In his description of the third-stage larva of this species, Neumann (9), on page 

 344, distinguishes it from G. intestinalis by its smaller size and its very deep red 

 colour. The absence of spines on the mid-dorsal region of the ninth segment is 

 mentioned and then- complete absence on segments 10 and 11. 



Hatching of the Eggs. 



There seems to be some doubt as to whether the eggs of bot-flies require moisture 

 and friction for their successful hatching. It has frequently been argued, notably 

 by Osborn (4) and later confirmed by Collinge (5), that both moisture and friction 

 are necessary factors in the hatching of the eggs of G. intestinalis. Whilst our 



