31$ E. H. STRICKLAND. 



legs had been in any way affected but a careful comparison of the 

 measurements of the legs of the parasitized ants with those of 

 healthy specimens failed to reveal any inhibition of theirdevelop- 

 ment on account of the Mermis, although the wings, which in 

 normal ants measured some 10-11 mm. in length were reduced 

 in the parasitized individuals to 6-6.5 nun. 



In the case of Sinnilium larvae, as before stated, the develop- 

 ment of the legs also is inhibited by the presence of Mermis, 

 though comparative measurements of the wings and leg histo- 

 blasts in healthy and parasitized larvae show that whereas in the 

 former case the wing histoblast covers about four times the area 

 covered by that of the mesothoracic leg, in parasitized larvae 

 these histoblasts bear a relation to each other in size of about 

 2.5 : i, showing that the wing histoblast suffered a greater inhibi- 

 tion in development than did that of the leg. 



A further interesting case of Mermis parasitizing ant larvae 

 was described by Wheeler ('10), in which case the worker larvae 

 of Pheidole commutata were parasitized, and resulted in the 

 adults of such larvae not only possessing all the normal " worker ' 

 characters perfectly developed, but owing to excess of feeding on 

 account of their constant hunger these " worker " larvae developed, 

 when mature, characters such as the ocelli which arc normally 

 only found in the sexual ants. 



A SPOROZOON PARASITE OF SIMULIUM LARVAE. 



While dissecting out worms from a batch of larva taken on 

 March 30, I chanced to cut open one larva which from the 

 whiteness of the abdomen I took to contain a worm, but was 

 much surprised to find that the body cavity was closely packed 

 with a white substance which had the appearance of cotton wool. 

 A little of this substance, however, when smeared on a slide was 

 seen to be composed of countless organisms as illustrated in 

 Plate V., Fig. 14. My first impression, very naturally, was that 

 these were spermatozoa, which they resemble very closely in 

 general outline. It was, however, very difficult to imagine to 

 what possible organism these spermatozoa could brlong. The 

 larva itself could surely not produce them; but it not tin- larva 

 what then? The only explanation seemed to IK' that they \\nv 



