GENUS VAGINICOLA. 715 



identification of the numerous species. Ehrenberg's primary separation of the 

 stalked from the sessile types under the title of Cothurnia, while not assented to 

 by many recent authorities, and formerly deprecated by the author,* may, it has 

 been decided upon, after fuller investigation, be conveniently retained. From 

 among the sessile series, or ordinary Vaginicoltz, may be further eliminated for 

 independent generic distinction the Vaginicola decumbens of Ehrenberg and several 

 other species corresponding with that type in the decumbent or adnate attachment 

 of the lorica recently described by De Fromentel, and upon which group as a whole 

 the title of Platycola is here conferred. A similar distinction may with justice also 

 be allotted to the Vaginicola valvata of Dr. Strethill Wright, with its remarkable 

 door-like valve, and to which are now added two other species, the three being 

 collated under the new generic name of Thuricola. Lastly, among the erect and 

 stalked Cothurnitz are found several forms agreeing with each other, but distin- 

 guished from the more normal species by the possession of an attached operculum ; 

 upon these it is proposed to confer the new generic name of Pyxicola. 



The considerable number of animalcules retained in the genus Vaginicola as here 

 defined are readily distinguished by their simple erect loricse, whose bases are 

 attached immediately to the chosen fulcrum of support without the intermedium of 

 a separate and distinct pedicle, and which possess, furthermore, no accessory hinged 

 valve or operculum-like stopper as a safeguard to the entrance to their domicile. 

 In many types varieties occur in which the posterior extremity tapers off to such an 

 extent as almost to present the aspect of such a distinct pedicle, but it will be 

 found on closer examination, that it never actually assumes, as in the genus 

 Cothumia, the character of such an independent structure. De Fromentel f has 

 proposed a partial subdivision of this genus, which while according in some respects 

 with the author's system, yields other features that do not recommend themselves for 

 adoption. His genus Vaginicola is thus made to include only the decumbent or adnate 

 V. (Platycola} decumbens and its allies, all the rest, either stalked or sessile, being 

 referred to the genus Cothurnia, which he again divides into three subordinate or 

 subgeneric sections, reserving the title of Cothurnia proper for the stalked forms, 

 Planicola for the stalkless ones, and that of Stylocola for certain types in which the 

 animalcule is attached posteriorly to the wall of the lorica through the intermedium 

 of several stylate processes. This last subgeneric group is here advanced to the 

 position of a new and distinct genus ; the author, however, is unable to concur with 

 the proposed substitution of the title of Planicola for those species universally 

 accepted as typical representatives of the genus Vaginicola. No distinction is 

 suggested by De Fromentel for the types included in the two genera Pyxicola and 

 Thuricola. 



Vaginicola crystallina, Ehr. PL. XL. FIG. i. 



Lorica transparent, subcylindrical or elongate pitcher-shaped, rounded at 

 the attached posterior extremity, slightly contracted towards the anterior 

 border, about three times as long as broad ; body of animalcule projecting, 

 when fully extended, for one-third of its total length beyond the orifice of the 

 lorica ; the parenchyma usually enclosing numerous bright green chlorophyll- 

 granules ; endoplast elongate, band-like. Length of lorica 1-210". 



HAB. Fresh water, on Lemna, Myriophyllum, and other water-plants. 



In common with other species of the genus Vaginicola and its allies, two animal- 

 cules produced through the longitudinal fission of one originally single zooid, are 

 frequently, as delineated in the accompanying illustration, found occupying the same 

 sheath or lorica. 



* 'Monthly Microscopical Journal,' vol. i., 1869. .f 'Etudes sur les Microzoaires,' 1876. 



