222 PROCEEDINGS OF THE ACADEMY OF [May, 



is sometimes saddle-shaped. While this peculiarity of contour is not 

 always so striking as here shown, the protomerite is always broad and 

 swollen in front, and much narrower behind. This serves to separate 

 this species from Gregarina achetoe-ahhreviatoe. In the satellites, the 

 protomerite is subspherical to compressed. 



Deutomerite. — Cylindrical, generally somewhat broader in front. 

 Outlines often irregular. 



Epicyte. — Very delicate. 



Sarcocyte. — Feebly developed, except in the anterior part of the 

 protomerite, where there is a conspicuous crescentic thickening. 

 According to my observations, this character was more marked in the 

 younger than in the older animals. 



Entocyte. — Not dense. 



Nucleus. — Moderate in size. 



Size. — Largest pair seen, 350 microns long. 



Habit. — Nearly always associated in pairs. Satellite generally 

 slightly and sometimes considerably smaller than the primite. When 

 the connection between a pair is broken, the anterior sm^face of the 

 protomerite of the satellite shows a slightly raised ring. Thus the 

 posterior end of the primite fits into a very shallow saucer on the 

 anterior end of the satellite. 



Movements. — The gregarines seen were more or less constantly 

 bending and contracting, but showed little or no disposition to progress. 



Cysts. — Round, occasionally oval. The cyst mass varies from 90- 

 110 microns in diameter. There is a cuticular wall 6-7 microns thick, 

 outside of which a gelatinous envelope develops. In newly formed 

 cysts, taken from the mid-gut of the host, the gelatinous envelope is 

 so diaphanous as to appear merely as a halo round the dense central 

 mass. But in cj^sts taken from the feces in the hind-gut, the gelatin- 

 ous envelope is much more evident. This change in appearance is 

 doubtless merely due to the accumulation of detritus. 



Of the cysts found in the host intestine, some are uniformly opaque, 

 with a clear space just inside the cuticle. Others are less opaque, 

 sometimes mottled; sometimes with an irregular dense central mass 

 and a clear periphery. These different aspects represent different 

 developmental stages, and indicate that maturation is rapid in this 

 species. This was confirmed by the behavior of cysts placed on slides 

 in a moist chamber. A considerable number, many of which had just 

 formed, were so isolated on July 2, and all were found to have dehisced 

 on July 4, no observation having been taken on July 3. The period 

 is thus 1-2 days, which is in close agreement with that of Gregarina 

 achetoe-ahhreviatoe. 



