238 on the organization of the genus gregarina of dufour. 



2. Gregarina Juli pusilli. 



While, translucent, oval. 



Cephalic sac hexahedral, with the sides rounded, or forming a double cone, base to base, with the upper apex 

 subacute, or truncated in younger individuals. 



Posterior sac robust, oval; granular contents, fine, translucent; interior corpuscle, globular, transparent; nucleus 

 transparent, without nucleolus. 



Whole length from the 1.1500th in. to the 1.275th in. 



Breadth of largest the 1.500th in. • 



Diameter of head of largest, 1.1500th in. 



Habitation. — Intestine of Julus pusillus. 

 Movements. — Its movements are not frequent. 



3. Gregarina Polydesmi virginiensis. 



White, translucent, clavate, spatulate, or oval. 



Cephalic sac campanulate, globular, or prolate, or oblate spheroid, surmounted by a papillary thickening of the 

 integument; interior granular mass very fine and translucent. 



Posterior sac globular, oval, clavate, spatulate, fusiform, or urceolate; posteriorly obtuse; parietal integument 

 wrinkled or distended ; granular contents very fine, faint, translucent; corpuscles, one or two, globular, transparent, 

 very faintly granular. 



Whole length from the 1.1000th in. to the 1.28th in. 



Breadth from the 1.1000th to the 1.430th in. 



Cephalic sac in largest 1.1400th in. long. 



Corpuscle 1.3000th to the 1.1000th in. in diameter. 



Habitation. — Intestine of Polydesmus virginiensis. 

 Movements. — Moderate and slow. * 



4. Gregarina Passali cornuti. 



White, opaque, in pairs, wrinkled. 



Cephalic sac hemispherical, without papillary thickening of the integument, interior granular mass opaque. 

 Posterior sac flaccid, when distended subglobular; granular contents opaque white, completely obscuring the 

 interior corpuscle. 



Average length, in pair, after distension, 1.66th in.; breadth, the 1.133d in. 

 Cephalic sac 1.260th in. at base; projects from body cell 1.533d in. 

 Muscular lines of the posterior sac 1.25000th in. apart. 



Habitation. — Proventriculus of Passalus cornutus. 



Remarks. — This species is usually found in pairs, the cephalic sac of one applied to the 

 posterior part of the posterior sac of another; a disposition from which Hammerschmidt 

 referred it to a new genus under the name of Clepsidrina. A very trifling degree of pressure 

 is sufficient to separate them from one another. 



Movements. — I never observed any other movement in this Gregarina than a slight con- 

 tractile one, commencing at the anterior part of the posterior sac and proceeding backward. 



• r >. Gregarina Achet.e abbreviate. 



While, opaque or translucent, with or without a proboscidiform appendage. 



Cephalic sac orbicular, or oval, without any papillary thickening of the integument, or occasionally with an 

 oval proboscidiform prolongation; interior granular mass opaque or translucent. 

 Posterior sac obeonic; granular contents opaque; interior corpuscle transparent. 



