220 PROCEEDINGS OF THE ACADEMY OF [May, 



THE POLYCYSTID GREGARINES OF THE UNITED STATES (Third Contribution). 

 BY HOWARD CRAWLEY. 



In 1853 Leidy described a gregarine parasite of the common cricket. 

 To this animal he gave the name of Gregarina achetoe-ahhreviatce, the 

 host being at that time known as Acheta ahbreviata. The parasite was 

 illustrated by figs. 32-34 of Leidy's plate 11. In my first communica- 

 tion on our gregarines (Crawley, 1903) I reproduced two of Leidy's 

 figures, and based my description partly upon these and partly upon 

 his text. A glance at these figures, Nos. 34 and 35 of my paper, will 

 suggest at once that they portray different species of gregarines, and 

 studies which I made during the summer of 1906 show that this is so. 

 For the animal shown in Leidy's fig. 34, copied in my fig. 35, I have 

 retained the name given by Leidy, while the other is tentatively placed 

 in the genus Stenophora. I have also considered it advisable to 

 redescribe Gregarina achetce-ahbreviatce, and have given a new figure, 

 a camera outline from a living solitary gregarine. 

 Gregarina aolietse-abbreviatae Leidy. (PI. XVin, fig. 1.) 



Gregarina achetoe-abbreviatoe Leidy (1853), p. 238, pi. 11, fig. 34. 

 Gregarina achetoe-abbreviatoe Crawley (1903), p. 45, pi. 3, fig. 35. 

 Gregarina achetoe abbreriatoe Crawley (1903o), pp. 639, 641. 



Protomerite. — Hemispherical to globular, broader than long. 

 Shape modified in the associations. 



Deutomerite. — Ellipsoidal to oval. 



Epiajte. — Thin, delicately striated. 



Sarcocyte. — Thin, but present all over the animal. 



Myocyte. — Easily demonstrated by the use of reagents. 



Entocyte. — Dense, but, following the usual rule, less dense in the 

 protomerite than in the deutomerite. In most of the specimens which 

 I'encountered, the peripheral part of the entocyte was almost free of 

 granules; this phenomenon being much more conspicuous in the deuto- 

 merite than in the protomerite. 



Nucleus. — Not seen. 



Size. — The largest solitary animal I saw was 500 microns long. 



Habit. — Solitary or associated in pairs. 



Cysts. — Spherical, provided with a thick gelatinous envelope 

 Diameter of cyst mass, 225-275 microns. Thickness of gelatinous 

 envelope, 30-300 microns. Dehiscence by sporoducts, 2-5 in number, 

 reaching a length of 1,000 microns. Prior to evagination, the situation 



