GENUS ANOPL OPHR YA. 567 



number, forming usually a single but sometimes a double longitudinal 

 series ; endoplast band-like, axial ; nearly as long as the body. Length 

 1-60". 



Hab. — Rectum and intestine of the fresh-water snail, Paliidina decisa. 



Professor Leidy, in describing this species * also as a species of Lciicophrys, 

 remarks that it is often so abundantly developed in its selected host as to completely 

 distend that portion of the intestine occupied, resembling in their crowded condition 

 a mass of writhing worms. Besides swimming with the aid of its cilia the species is 

 capable of effecting progress after the manner of a worm by the contortions of its 

 body, which may be flexed into a sigmoid contour or be even doubled upon itself. 

 The endoplast, while scarcely perceptible in the fresh condition, becomes clearly 

 delineated as the animalcules approach dissolution. 



Anoplophrya convexa, Clap. sp. 



Body oval, mcniscoidal, obtusely rounded at each extremity, about one 

 and a half times as long as broad ; cuticular surface finely striate longitudi- 

 nally ; contractile vesicles very large, varying in number from four to six, 

 forming a unilateral row ; endoplast axial, about half the length of the body. 

 Length 1-178". 



Hab. — Marine, within a species of Pkyllodocc, separate from that infested 

 by Anoplophrya ovata. Multiplication by fission or segmentation not 

 observed. 



This and the three succeeding species are not included by Claparfede and Lach- 

 man in their larger work ' i^tudes sur les Infusoires,' but are described by Claparfede 

 only, in his ' Recherches sur les Annelidas Turbellarit^s observes dans les He'brides,' 

 published at Geneva in the year i860. All four are there referred to the typical 

 genus Opalina. 



Anoplophrya ovata, Clap. sp. 



Body ovate, equally rounded at each extremity, not quite twice as long 

 as broad ; cuticular surface longitudinally striate ; contractile vesicles 

 spherical, five or si.x in number, forming a single lateral row ; endoplast 

 axial, elongate, about one-half the length of the body. Length 1-200". 



Hab. — Marine, within a species of Phyllodoce. Multiplying abundantly 

 by segmentation of the posterior region, the endoplast taking its share in 

 the division. 



Anoplophrya filum, Clap. sp. Pl. XXVI. Fig. 13. 



Body ribbon-like, flattened, long and slender, about twelve times as long 

 as broad ; cuticular surface finely ciliate throughout, the cilia at the posterior 

 extremity slightly longer, forming a somewhat brush-like tuft ; cuticu- 

 lar surface granular, not conspicuously striate ; contractile vesicles minute, 

 numerous, about twenty in number, forming a single subcentral row ; endo- 

 plast not observed ; increasing, as in A noplophrya lineata and A . prolifera, 

 by posterior segmentation. Length 1-65". 



Hab. — Marine, within the alimentary canal of Clitellio arcnarius. 

 * ' Proc. Acad. Nat. Sci. Philadelphia,' 1877, p. 259. 



