632 ' PROCEEDINGS OF THE ACADEMY OF [Oct., 



THE POLYCYSTID GREGARINES OF THE UNITED STATES.-Second Contribution. 



BY HOWARD CRAWLEY. 

 I. 



The following paper contains the results of my observations on 

 gregarines during the spring and summer of 1903. Two new genera 

 and several new species have been discovered. In addition, some 

 observations on the biology of the animals are described. These con- 

 cern the cysts and the time required for the maturation of the spores. 



II. 



ACUTISPORA n. g, 



Cysts spherical, with a thick cuticular membrane. Dehiscence by 

 means of an annular pseudocyst, which develops around one end of 

 the ellipsoidal spore-mass, the two together having the form of an 

 acorn. Spore-mass ellipsoidal and enclosed in a tough transparent 

 membrane, which splits into two values by a rupture extending around 

 the major diameter. ^Maturation period intermediate. 



Spores large, navicular in shape and showing epispore and endo- 

 spore. Ordinarily symmetrical, but sometimes with the longer axis 

 very slightly curved. Endospore a truncated double cone, but with 

 a slightly curved profile, and furnished at either end with a thick, blunt 

 refractive rod, the whole covered over by the epispore. Within 

 a large spherical residuum, either central or lateral, around which the 

 sporozoites are grouped. 



The genus contains one species: 

 Acutispora macrocephala n. sp. PI. XXX, figs, 1-6 



Epimerite: Some of these animals showed an anteriorly directed pro- 

 longation of the protomerite which may possibly be regarded as con- 

 stituting the epimerite. If so, this element is poorly developed and 

 differs considerably in the different individuals. In some cases the 

 entocyte extended into it. 



Protomerite: Always showing a deep constriction at the beginning of 

 the posterior third. Large, and relatively larger in the small than in 

 the large animals. Separated from the deutomerite by a sharp con- 

 striction. 



