GENUS VORTICELLA. 667 



Pyxidium cothurnoides, S. K. Pl. XXXIV. Fig. 7. 



Animalcules ovate, somewhat gibbous, twice as long as broad ; peristome 

 margin truncate, entire ; ciliary disc minute, furnished with two circlets of 

 cilia, projecting conspicuously beyond the border of the peristome ; surface 

 of cuticle smooth, considerably indurated ; endoplast linear, curved, longi- 

 tudinally placed ; contractile vesicle adjacent to the vestibulum ; pedicle 

 very short, less than one-quarter the length of the body, which it supports 

 in a slightly inclined or oblique position. Length of body 1-500". 



Hab. — Fresh water, attached to Entomostraca. 



The examples which served as a basis for this new species and genus were 

 obtained by the author, in March 1874, attached in considerable quantities, singly 

 or in small groups, to the carapace of a species of Cypris. Deprived of its short 

 pedicle and with its body laterally attached, this type would have to be referred to 

 the genus Lagenophrys, and may be regarded as intermediate between Operailaria 

 and that genus. The zooids on contracting exhibit a nodding action, and become 

 bent obUquely on their short pedicles, but in consequence of the rigidity of the 

 integument scarcely alter their general contour. Although looked for, no distinct 

 membranous collar, as in Operailaria^ could be detected. More than twenty 

 specimens of this animalcule were observed on a single Cypj'is obtained from a 

 pond at Stoke Newington. Some of the older zooids were a pale amber colour, 

 the younger ones being perfectly transparent. 



Pyxidium inclinans, Mull. sp. PI. XXXIV. Fig. 9. 



Body erect, ovato-cylindrical, posterior extremity rounded and widest ; 

 the cuticular surface finely striate transversely; peristome-border longi- 

 tudinally plicate ; ciliary disc protrusible to a considerable distance beyond 

 the margin of the peristome, bearing one ciliary circlet, supplemented by 

 a collar-like membrane ; pharyngeal cleft conspicuous, prolonged through 

 two-thirds of the length of the body ; pedicle very short and stout ; body 

 when contracted transversely folded posteriorly, remaining erect or bent 

 to an entirely recumbent position. Length of body 1-300". 



Hab. — Fresh water. 



This species, introduced by De Fromentel * under the title of Scyphidia incHna/is, 

 and identified by him with the Vorticella inclinans of O. F. Miiller, is apparently 

 referable to the present genus. From the form last described it may be easily 

 distinguished by its more regularly ovate form and by the various transverse and 

 longitudinal striae and plications of the cuticular surface. No details of the special 

 habitat of this variety are recorded by De Fromentel, but the two examples are 

 apparently attached to a Confervoid filament. 



Genus VIL VORTICELLA, Linnsus. 



Animalcules ovate, spheroidal or campanulate, attached posteriorly by a 

 simple, undivided, more or less elongate and contractile, thread-like pedicle ; 

 the pedicle enclosing an elastic, spirally disposed, muscular fibrilla, and 

 assuming suddenly on contraction a much shortened and usually cork- 

 screw-like contour ; adoral system consisting of a spirally convolute 



* ' Microzoaires,' 1876. 



