632 PESCKIPTION OF [Rotatoria. 



the various Systolides more or less like Hydatina, in their club- 

 shaped form and articulated tail, such as Notommata petromyzon, 

 N. najas, N. gibba, and probably also Eosphora najas, E , dignitata, 

 and E. elongata (Ehr.) We moreover refer provisionally to the 

 genus Furcidaria several other Systolides considerably dissimilar in 

 form, some being very long, with two very long styles, of which 

 Ehrenberg makes his Notommata longiseta, and N. oequalis, and 

 his genus Scandium ; whilst others have an ovoid, thick body, 

 rounded posteriorly, truncate in front, and with a short oblique 

 tail, which Ehrenberg calls Notommata myrimeleo, and N. syrinx. 



All these Ftircidaria except F. marina, to which F. Reinhardti of 

 Ehrenberg must probably be added, have been found in fresh water; 

 but it is most likely the number of those living in the sea are much 

 more numerous, and I have indeed myself met with three or four 

 distinct species, which I have from want of time not yet described. 



FuRCULARiA gibba. — Body oblong, slightly compressed, under 

 side flat, back convex, toes forked, long (styliform), equal to half 

 the body ; the eye is placed upon a nervous ganglion over the 

 mouth, clearly, indicating the dorsal surface ; the ovarium has, 

 generally, one large and ripe ovum ; the movement of this ani- 

 malcule is somewhat slow. Found in green water, and amongst 

 Conferva. Length l-96th. 



F. Reinhardti. — Body fusiform, truncated in front, foot elongated, 

 cylindrical, and shortly furcate at the end ; a slight stricture divides 

 the body and head. P. 9, fig. 397, represents an animal extended, 

 and fig. 398, another, contracted ; the former is a side (right), the 

 latter a back, view. Found as a parasite upon Monopyxis (Sertu- 

 laria) geniculata, in sea water. Length l-120tli. 



F. forficula. — Body cylindrical, obtusely pointed in front, rounded, 

 and dentated at the base, on the upper side ; the toes very long ; 

 the rotatory organ appears to have two frontal clusters of cilia near 

 the eye, and a wheel-like bundle on each side. Length l-144th. 



F. gracilis. — Body slender, cylindrical, suddenly attenuated at 

 the base of the furcate foot ; toes straight, long, but shorter than 

 half the body. The rotatory organ appears disposed on six 

 muscular masses, between, and superior to which, is a longish 

 central ganglion, with a red eye. In green water. Length l-180th. 



