682 ORDER PERITRICHA. 



This species, as figured and described by O. F. Miiller,* possesses a just claim 

 for recognition in this treatise, no spheroidal type with a pedicle of so great a 

 relative length ha\ang up to the present time been recorded by any more recent 

 investigator. So far as it is possible to judge, comparing Miiller's drawings with 

 the figures given by him of other well-known species, the diameter of the body of 

 this animalcule is about 1-150". Its habitat being so clearly defined, its rediscovery 

 may be anticipated. 



Vorticella sphaerica, D'Udek. Pl. XLIX. Fig. 23. 



Body spherical, nearly as broad as long, its surface smooth ; pedicle 

 short, about twice the length of the body, comparatively thick ; peristome- 

 border and ciliary disc small and contracted, the latter structure but 

 slightly elevated. Length 1-820". Hab.- — Fresh water. 



This species was obtained by D'Udekem from the AVillebroeck Canal, near 

 Brussels. No allusion is made in his description to either its solitary or social 

 habits. 



Vorticella margaritifera, From. Pl. XLIX. Fig. 24. 



Body spherical, hyaline, granulate, enclosing brilliant refringent cor- 

 puscles ; ciliary wreath very minute, vestibular fossa large ; pharyngeal cleft 

 deeply prolonged, conspicuously ciliate ; pedicle short and stout, twice the 

 length of the body, its attached or proximal extremity conspicuously dis- 

 coidal. Length 1-400". Hab. — Fresh water. 



De Fromentel f remarks of this species that it can close its ciliary disc without 

 contracting its pedicle ; as also, that the pedicle does not retract in a spiral form but 

 is simjily shortened by the closer apposition of its annular rings, its external trans- 

 parent sheath becoming at the same time transversely wrinkled. The body in 

 general form, while of smaller size, corresponds closely with the species last 

 described. 



Vorticella mamillata, From. Pl. XLIX. Fig. 25. 



Body almost spherical, smooth and transparent, slightly granular; peri- 

 stome narrow, projecting when expanded in the form of three nipple-like 

 papillae ; pedicle moderately thick, two or three times longer than the body. 

 Length 1-750". Hab. — Fresh water. 



Vorticella constricta, From. Pl. XLIX. Fig. 26. 

 Body subspheroidal, smooth, granular, slightly flattened ; peristome- 

 border very narrow, taking the form of two raised papillae surmounted by 

 prominent vibratile cilia ; oral fossa situated between these papillae, followed 

 by a short pharyngeal cleft; the posterior extremity exhibiting at its junc- 

 tion w ith the pedicle a short conical prolongation ; pedicle slender, about 

 twice the length of body, contracting in a zigzag and not in a spiral manner. 

 Length 1-530". Hab. — Fresh water. 



This species appears to be closely allied to the Vorticella mamillata of the same 

 author, last described. The papilhfonn prominences in either case possibly represent 

 an abnormal condition only of the peristome and ciliarj' disc. 



' Animalcula Infusoria,' p. 313, tab. xliv. fig. 14. f 'Etudes sur les Microzoaires,' 1S76. 



