THE CANADIAN ENTOMOLOGIST 409 



found to be parasitised with species of two distinct Protozoan 

 orders — namely, Gregarinida and Myxosporidia S. L. The former 

 was represented by a single species, the taxonomic position of which 

 was not ascertained. Larvae parasitised by this species were con- 

 spicuous in presenting a white speckling over the entire surface of 

 the body (fig. 4). This, upon closer examination, was seen to 

 be due to innumerable small globular cysts, measuring up to .25 

 mm. in diameter, which either floated freely in the blood, or were 

 still attached to the original seats of infection. The tissues invaded 

 were the ectodermal epithelium, the cells of the fat body and the 

 layer of pigment cells which cover the nervous system in these 

 larva. The sexual organs Avere never found in parasitised larva?. 



The cysts when sectioned, and stained with iron hfematoxylin, 

 were seen to be composed of a homogeneous mass of granular proto- 

 plasm, in which w^as situated numerous free masses of chromatic 

 material. In some young cysts there were vacuoles, but these 

 were detected in living specimens only. In other fresh material 

 there seemed to be a distinct ectosarc layer of a perfectly clear fluid. 

 By the end of November a developmental stage was reached in 

 wnich the protoplasm began to collect around the scattered masses 

 of nuclear material, and the cyst contents were divided up into 

 numerous uninucleate globular bodies. If a cyst were then dis- 

 sected and allowed to float in water it soon bursts, liberating count- 

 less numbers of these minute globules which, within a quarter of 

 an hour of their escape, began to move independently,and were soon 

 actixely darting around, in a limited area, in the water. Killed 

 and fixed specimens revealed the fact that each was provided with 

 a flagellum . No further study of these organisms was made. 

 The larva? thus parasitised had their histoblasts retarded, though 

 to a less extent than those which contained Mermis sp. Since 

 this parasite was present in about 50% of the larva? in streams 

 where it was found, it must have a distinct economic value. The 

 retardation of the histoblasts is sufiiciently pronounced to assure 

 the death of the larva^, which was in all recorded cases that of 

 5. bractealum. No other species of Simulium larvae were present 

 however, in the streams where this parasite was found. 



The order Myxosporidia S.L. was represented by three species 

 ol the genus Glugea. These species recei\'ed special attention, and 



