GENUS VORTICELLA. 675 



having, as seen in optical section, ten to each row, divided by a hyaline central 

 space. The author has entirely failed to corroborate Everts' interpretation of this 

 structure, but has at the same time observed, in the case of Vorticella nebulifera, 

 V. campanula, and many other species, the presence of a more or less even layer of 

 granular corpuscles intervening between the hyaline outer sheath and the denser, 

 but apparently homogeneous central cord. A similar composition has been also 

 observed to obtain in the homologous structure of the compound type Carchesium 

 polypinum, of which indeed the author has succeeded in making preparations that 

 distinctly show the existence of these three elements, as indicated in Fig. 3 of the 

 accompanying woodcut. As there shown, this granular layer is distributed upon the 

 surface of a delicate hyaline membrane which encloses the central cord that both won- 

 derfully resembles, and physiologically corresponds with, the delicate external sheath 

 or " sarcolemma " of ordinary muscular tissues. 



Vorticella picta, Ehr. PL. XLIX. FIG. 2. 



Body conical-campanulate, about twice as long as broad, frontal 

 margin widest, slightly everted, parenchyma transparent ; cuticular surface 

 smooth ; pedicle slender, four or five times the length of the body, enclosing 

 an even linear series of minute scarlet corpuscles. Length i-i 1 50" to 1-570". 

 Inhabiting fresh water, social. 



This species was obtained by Ehrenberg, growing abundantly on Salvinia natans, 

 at Pickelsburg, in the neighbourhood of Spandau on the Spree, in the year 1831, 

 but does not appear to have fallen beneath the observation of any subsequent 

 investigator. The peculiar character of the pedicle affords a ready clue to its future 

 identification. 



Vorticella gracilis, Duj. PL. XLIX. FIG. 3. 



Body evenly conical, about twice as long as broad, the anterior margin 

 widest, slightly everted ; parenchyma transparent ; cuticular surface smooth. 

 Length 1-520". HAB. Marsh water, after long keeping. 



No description of this species is given by Dujardin, but simply an illustration of 

 the body and a small portion of the pedicle of a single zooid, with a notification 

 of its habitat, as above. 



Vorticella brevistyla, D'Udekem. 

 PL. XXXIV. FIGS. 13 AND 14, AND PLATE XLIX. FIG. 4. 



Body ovate, nearly twice as long as broad, tapering posteriorly when 

 extended, spheroidal with a small anterior nipple-like projection when 

 contracted ; peristomal border rather narrower than the centre of the body, 

 not everted ; pedicle about half the length of the extended body, decumbent, 

 and forming half a spiral turn only when contracted. Length 1-300". 



HAB. Pond water. 



This species, as described by D'Udekem * and obtained from pond water near 

 Brussels, closely resembles, with reference to the shortness of the pedicle, the forms 

 already described under the titles of Pyxidium and Rhabdostyla. The encystments 

 of the animalcule, as observed by D'Udekem, are of a brownish hue, subspherical, 

 with numerous angular asperities. 



* ' Infusoires de la Belgique,' 1864. 



P 2 



