7^8 ORDER HYPOTRICHA. 



have been banished from zoological taxonomy. The genus Huxleya, as typified by 

 H. crassa, differs from Trochilia in its naked, non-encuirassed cuticular surface, 

 in its almost perfectly cylindrical instead of flattened contour, and in the absence 

 of the long cilium or seta that projects from the oral region. Unfortunately, 

 Claparede and Lachmann failed to ascertain whether the pharynx was armed after 

 the manner of the ordinary Dysteriidae, though no doubt this structural element 

 will be found, on further investigation, to exhibit characters of important diagnostic 

 value. 



Huxleya crassa, C. & L. Pl. XLII. Figs. 37 and 38. 



Body oval, subcylindrical, equally rounded at the two extremities, 

 about one and a half times as long as broad ; a raised circular border 

 developed at a short distance from the posterior extremity, such border 

 imparting to the animalcule, in conjunction u^ith the rounded caudal region 

 and appended style, an acorn-like aspect. Length of body 1-350". 



Hab. — Salt water : Norwegian coast (C. & L.). 



Genus VII. TRICHOPUS, C. & L. 



Animalcules free-swimming, not encuirassed, compressed, the narrow 

 band-like ventral surface entirely ciliate, terminating posteriorly in a 

 compact fascicle of setose cilia, which takes the place of the caudal style 

 in the preceding Dysteriidae ; oral aperture followed by a cylindrical 

 pharyngeal rod-fascicle;' endoplast single, ovate ; contractile vesicle single, 

 spherical, situated near the posterior extremity. 



Trichopus dysteria, C. & L. Pl. XLII. Fig. 46. 



Body subpyriform, about twice as long as wide, largest and inflated 

 posteriorly, abruptly narrowed towards the anterior extremity ; the dorsal 

 and lateral surfaces entirely smooth ; the posterior ciliary fascicle short and 

 pointed, having a styloid aspect. Length of body 1-200". 



Hab. — Salt water : Norwegian coast. 



Though no reference to such a structure is made in the text, Claparede and 

 Lachmann represent, in their illustration of this species, a smgle long recurved cilium 

 as projecting from the anterior extremity, and which, if it actually exists, probably 

 corresponds with the somewhat similar projecting oral cilium or seta developed 

 in the genus Trochilia. The posterior fascicle of cilia in this type — apparently homo- 

 logous with the single stylate appendage occupying the same position in the ordinary 

 Ervilinae — is of especial interest, its origin and significance being comparable with 

 the analogous structure subsisting in the Peritrichous Urocentnim, with reference to 

 the genus Gyrocorys. 



Fam. IV. PERITROMIDiE, Stein. 



Animalcules free-swimming, ovate or reniform, with a plane ventral and 

 convex dorsal surface ; the oral aperture ventral, debouching upon the 

 posterior angle of an excavated peristome-field, the outer or left-hand border 

 of which bears an arcuate fringe of large powerful adoral cilia or cirri ; 



