OF THE OPHRTDIXA. 601 



include Opliiydiiia), since it is ciliated all round, and differs greatly from them 

 in the form of its alimentary apparatus. Moreover, a species inhabiting a 

 gelatinous sheath occurs in the freshwater ponds in the Thiergarten at Berlin. 



TiXTiNNUS inquilinus. — Hyaline or 

 yellc^asli ; lorica cylindi-ical, glass-like, 

 bell-shaped. 1-570", with stalk 1-240". 

 lu sea- water, on xilgae. 



T. subulatus ( Vorticella vaginata, M.). — 

 Hyaline ; sheath conical, with a posterior 

 subulate elongation. Ehrenberg obseryes 

 that, if this elongation of the lorica Avere 



called a stalk, we shoidd require a new 



drical, hyaline, indistinctly annidar : ra- 

 ther attenuate and truncate posteriorly. 

 1-440". In the Baltic. 



T. Campanula. — Hyaline; sheath widely 

 campanulate, dilated in front, pointed 

 behind. 1-290". In North Sea and 

 Baltic. 



T. denticulatus. — Sheath cylindrical, 

 hyaline, sculptured with oblique rows of 



generic name for the animalcule. Length I dots, fi-ont margin acutely dentate ; pos 

 of lorica 1-90". terior extremity pointed. 1-220". In 



T. Cothurnia. — Hyaline ; sheath cylin- ! the North Sea. 



Genus YAGINICOLA (XXYII. 10, 11 ; XXYIII. 18, 19).— Neither the 

 body nor the lorica stalked ; a Avreath of cilia surrounds the truncated front 

 portion, mthin which is the orifice or mouth. The polygastric apparatus, 

 the passage of the food onwards, its return, and the exit of the refuse near 

 the mouth, and coloured ova-granules, are mentioned by Ehrenberg. In- 

 crease by longitudinal self-division of the body (not of the lorica) has been 

 seen in all the species. 



To the above account must be added, according to Stein's observations, 

 that the body of Vaginicola has in front a peristom, from out of which a 

 " rotary apparatus " protrudes, consisting of a ciliated disc, supported on a 

 stout stem or pedicle, just like that of Vorticella. A mouth opens on one 

 side of the disc, and leads into an cesophagus ; but no polygastric structure, as 

 sui'mised by Ehrenberg, is \isible, although numerous alimentary vacuoles 

 are usually present. Ova-granules, again, are merely hypothetical, and, as 

 in other Infusoria, where mentioned by Ehrenberg, represent particles of 

 various kinds, but mostly coloured granules. In a new species noted by 

 Dr. Wright, the tubular sheath has a peculiar structm-e in the form of a 

 valve, which closes over the animalcule when it retreats to the bottom of its 

 case (XXYIII. 18, 19). 



In all the particulars of internal organization, Vaginicola resembles Vorti- 

 cella. Propagation by fission and gemmation is very distinct ; by the former 

 process more common (XXYII. 10, 11). The development of the bud takes 

 place from the base of the parent, and within its sheath. The young being, 

 produced by either process, is furnished, as in Vorticella, with a posterior 

 wreath of cilia, whilst it is endoAved with free locomotion (XXYII. 11). It 

 frequently happens, as represented in the last-quoted figure, that the young 

 being assumes on its formation a contracted ovoid foiTu, with its frontal Avreath 

 retracted. Upon the appearance of the posterior whorl of cilia, and aided by 

 its movements, the animal loosens itself, escapes from the parent-case, and 

 swims freely away, elongating itself, it may be, if previously contracted, and 

 assuming finally all the characters of a perfect Vaginicola, by developing 

 around it its own special sheath. 



On the other hand, the contracted indiA-idual may become actually encased 

 within its integument (in other words, encysted), and, as Stein believes, 

 may thereupon assume all the characters of an Acineta, and eventually give 

 birth to a ciliated embryo (XXYII. 11-15). This metamorphosis, however, 

 is not generally accepted. The specific characters in this genus are for the 

 most part deduced from the figure and dimensions of the external sheath or 

 lorica (Ehr.), and must, therefore, as Stein points out. be admitted with much 



