74 ILLINOIS BIOLOGICAL MONOGRAPHS [284 



mal either with or without the use of a stain on the slide. Ameboid move- 

 ment was noted, chiefly confined to the anterior part of the deutomerite ; 

 it results in the nodding of the 'head' as many as thirty times without 

 ceasing or decreasing speed. The protomerite does not change in shape 

 or size, neither does the posterior two thirds of the deutomerite. The 

 epicyte of the shoulder region stretches on one side, the endocyte flows 

 into the pocket thus formed, and the inactive protomerite, its equilibrium 

 disturbed, drops to one side and then to the other as the pockets form 

 now on one side and now on the other. Structures which cause move- 

 ment must therefore be much more numerous or else much more active 

 physiologically in this restricted area than elsewhere. 



Cysts are spherical and vary from 150 to 270/1. in diameter. I have 

 as yet been unable to procure development of the cysts. A number were 

 kept from two days to two weeks in water and normal saline media and 

 when opened revealed no indication of having undergone progression 

 beyond the dissolution of the walls separating the two conjugants. 

 Staining revealed no differentiation whatever in the apparently homo- 

 geneous protoplasm. 



This species is distinguished from Stenophora larvata (Leidy) Ellis 

 by the considerable difference in size. Leidy 's species varies from lOOfx 

 to 800/x in length, while 8. lactaria does not exceed 480/a. His form varies 

 in width from 30/i to 20/i,, the other never exceeding 90/x. The ratio of 

 length protomerite : total length in S. larvata (largest individual) is 

 1 : 26 ; in S. lactaria it never exceeds 1 : 16. The nucleus in the for- 

 mer is spherical and about 10/x in diameter; in the latter it is ellipsoi- 

 dal and smaller, 55 by SO^u, in the largest measured. The host is a differ- 

 ent diplopod found, however, in the same habitat. 



8. lactaria differs from 8. elongata Ellis and from 8. cockerellae 

 Ellis in size, shape of the protomerite and deutomerite, and in shape espe- 

 cially of the posterior end of the deutomerite. 



STENOPHORA DIPLOCORPA Watson 

 [Figure 54] 

 1915 8tenophora diplocorpa Watson 1915 :29 



A number of most peculiar polycystid gregarines were found in the 

 common small diplopod, Euryurus erythropygus (Brandt), at Ur- 

 bana, Illinois. . The parasites were abundant in each of the two speci- 

 mens examined, each host containing more than a dozen gregarines. 



The sporonts are solitary. The shape is more or less cylindrical, the 

 body being very much attenuated. The protomerite is as wide as it is 

 long and is from one-sixteenth to one-twenty-fifth the total length of the 



