008 DESCKIPTION OF \Rolalofia. 



several families Phjgura, Oecistes, and Co7iochilus. For Dujardia 

 states that the individuals of these three genera present no further 

 diflfierences than in the gelatinous envelope, which surrounds the two 

 last, forming in Oecistes a distinct tube for each individual, whilst 

 it includes the individuals of Conochilus in a common globular mass, 

 and is absent in Ptygura. The same author would name Oecistes, 

 Ptygura crystallina, and the several Conochili, Ptygura volvox. 



Ptygura melicerta. — Transparent ;^body cylindrical, club-shaped, 

 turgid anteriorly, with two little curved horns at the mouth, and a 

 single short tube at the neck (?). The tail-like foot always re- 

 mains transversely folded (wrinkled), as seen in fig. 354, P. 7, 

 which represents the under side. When swimming, a ring-like 

 simple vibratile organ is thrust out with a lateral notch. The two 

 jaw-like parts of the oesophageal bulb have numerous teeth, as 

 represented at fig. 355, Size l-140th. 



Genus Dasydytes (Gosse.) — Eyes absent ; body furnished with 

 bristle-like hairs ; tail simple, truncate. 



This genus, according to Ehrenberg's description of Icthydina, 

 must follow after Ptygura. 



D. goniothrix. — Hairs long, each hair bent with an abrupt angle ; 

 neck constricted. Length l-146th. Found at Leamington. 



D. antenniger. — Hair short, downy ; a pencil of long hairs at 

 each angle of the posterior extremity of the body ; head furnished 

 with two club-shaped oi'gans resembling antennae. Length 1-1 70th. 



Genus Iciithydium. — The ciliated fish ^mma?eM?e« have a cleft 

 or forked foot-like tail ; no eyes or hair ; currents at the mouth, 

 and along the ventral side, indicate the existence of a vibratile organ, 

 which not only serves for swimming, but likewise for creeping. A 

 long oesophagus, a thick simple conical alimentary canal, and 

 sometimes a large single ovum, comprise our knowledge of their 

 organization. It is probable that a cylinder of little wand-like 

 teeth exists. 



I. iiodura {Cercaria podura, M.) — Body straight, oblong, often 

 slightly constricted anteriorly, where it is turgid, and sometimes 

 three-lobed. It is colourless or whitish, but during repletion some- 

 times appears yellowish ; the ventral surface is flat and ciliated, the 

 dorsal arched and smooth. The large dark ovum has been seen by 



