156 ILLINOIS BIOLOGICAL MONOGRAPHS [366 



width deutomerite : : 1 : 1.3. The protomerite is cone-shaped, constricted 

 above the middle, and terminates in almost every instance in a small epi- 

 merite. This structure in youngest individuals is a simple short spike ; 

 as the animal grows older it becomes a sphere, and finally becomes cup 

 shaped. Old sporonts sometimes lose this epimerite. The protomerite 

 is widest at the septum and there is here a slight constriction which may, 

 however, be lacking. The deutomerite is ovoidal, widest at the shoulder 

 just below the septum, and terminates in a broadly rounded or slightly 

 tapering posterior end. The nucleus is visible in young individuals as 

 a minute spherical body. 



The protoplasm is dense in the deutomerite, being black in trans- 

 mitted light; it is nearly as dense in the lower half of the protomerite, 

 but the upper portion of the latter is nearly devoid of endoplasm. The 

 epimerite is clear. 



Cysts are dense, spherical and average 120/a in outer diameter. The 

 inner diameter is approximately 90/*. Spores were not seen. 



Figures for a few individuals measured are as follows ; dimensions 

 are given in microns : 



Total length sporont 200 150 105 



Length protomerite with epimerite 80 65 50 



Diameter epimerite _ 20 20 18 



Length protomerite alone 60 45 32 



Length deutomerite _.... 120 85 70 



Width protomerite 90 50 105 



Width deutomerite 100 80 105 



Ratio 



length protom. (without epimerite) : total length_.l :3.3 1 :3.3 1 :3.3 



width protom. : width deutomerite 1 :1.1 1 :1.6 1 :1 



This species differs from the other species found in the genus Har- 

 palus as follows: Gregarina parva (Crawley) Watson and Hirmocystis 

 harpali Watson are both associative ;AchVwcep/iaZws gvmbeli (Ellis) 

 Watson differs in size and proportions (the epimerite was not seen in the 

 latter species) ; in Actinocephalus harpali (Crawley) the maximum length 

 of the sporonts is 1200/a, and in proportions and sizes of cysts (640/x, in the 

 latter), the two species are widely different. 



The species is placed in the genus Steinina because the epimerite 

 is a short mobile digitiform process changing through a sphere into a 

 flattened button ; the sporonts are small, solitary and obese ; the proto- 

 merite terminates in a large cone ; the cysts are small. 



It differs sufficiently in size range from the three other species 

 described in this genus to be designated a separate species. 



