Protozoa and Rot if era at Havana, III. 309 



anterior part of the ventral surface, triangular, and partly 

 surrounded by the adoral wreath. Stylonichia may be re- 

 garded as typical of this group. Its body is elongate, rounded 

 at the ends, and persistent in shape. The cilia form a con- 

 tinuous border around the ventral margin. The peristome- 

 field is placed anteriorly on the left side of the ventral surface. 

 It is well supplied with cilia and with a band-like undulat- 

 ing membrane. A number of the frontal cilia are modified 

 into styles. There are several claw-like caudal setse, and some 

 anal spines. The contractile vacuole is single ; the nuclei 

 two in number, usually oval. 



In the Peritricha the cilia are usually limited to an adoral 

 wreath at the expanded end. Sometimes a circlet is present 

 at the opposite end. The well-known Vorticella, or bell ani- 

 malcule, is a good example of this group. The body is 

 spheroidal or more or less bell-shaped, and the ectoplasm is 

 prolonged posteriorly into a stalk, by means of which the 

 animal is attached. The myophan fibrils of the body unite 

 and form a large contractile muscular fiber extending through- 

 out the length of the stalk. The cuticular surface is some- 

 times transversely striated and otherwise ornamented. The 

 right limb of the adoral ciliary wreath descends into the 

 pocket or vestibulum, at the bottom of which the oral opening- 

 is situated. Contractile vacuoles one or several ; nucleus 

 band-like, large. 



The subclass Suctoria is the most highly differentiated of 

 the Infusoria. This is especially seen in the matter of repro- 

 duction, for many of them reproduce by internal budding. 

 Tolcophrya may be considered as a type of this group. The 

 body is usually persistent in shape, more or less oval, and 

 fastened by the attenuate posterior end to a rigid stalk. In- 

 stead of cilia, the adult forms have a number of fine hair- 

 like tentacles, either scattered irregularly over the anterior 

 surface or arranged in several fascicles. These tentacles are 

 slightly movable and may be extended or retracted, serving 

 to capture prey and to convey food substance into the body ; 

 for, notwithstanding their slender form, particles of food from 

 the mass being fed upon may be seen passing within these 



