94 



S. HADWEN AND A. E. CAMERON. 



abruptly (fig. 4). The chorion encircled by a close series of fine striae, bearing on 

 their anterior margins tiny, slightly recurving spinules anteriorly directed, the 

 spinules of any one stria all but reaching the stria immediately anterior. Egg 



Pig. 4. Egg of GastropMlus haemorrhoidalis ; outline 



sketch to show attachment to hair and disposition jjf 



bands on stalk, X 65. 



disposed parallel to the hair, with the exception of a shght outward "deviation of the 

 unflanged anterior portion. Operculum placed antero-externally, non-striate and 

 non-reticulate, elongate-oval, slightly concave on its inner side (fig. 5). 



G. haemorrhoidalis generally lays its eggs on the hairs of either of the lips of the 

 horse, but preferably on those of the lower. Parker (7), among other authors, states 

 that the eggs are also found in the nostrils, but it has never been our experience to 

 find them elsewhere than on the lips. 



According to Parker (7), eggs of this species were found by himself and his 

 assistant thrust into the nose and lips of horses, sometimes to the full length of the 

 stalk. Thus he finds a reason for the nervous and occasionally uncontrollable fear 

 shown by horses when the fly is " striking." Further, he states that the chitinous 

 " bands " of the stalk impart to it the appearance of a screw, and that the structure 



Fig. 5. Egg of GastropMlus haemorrhoidalis removed liom 

 the hair to show the continuity of the flanges with the 

 stalk, X 69. 



is patently adapted to hold the egg in the skin after insertion. In no single instance 

 did we find the egg penetrating the skin. On the contrary, we invariably found it 

 adhering to a hair (fig. 4) and not touching the skin. Therefore, we conclude that 

 Parker must have erred in his observations. 



The recently emerged Larva. 



GastropMlus intestinalis. 



Number of segments 13, hairless. Length, 0-866 mm. ; greatest width, 0-217 mm. 

 General colour translucent white ; general shape strap-like and fusiform, tapering 

 towards both extremities. Unpaired, lance-like mouth-stylet (mandible) directed 

 anteriorly. Anterior margin of the first segment with a few recurving, small, black 

 hooks. Anterior margin of the second segment bearing an armament of long, 

 recurving, black hooks (head-hooks), diminishing in size posteriorly, interspersed 



