KOTIFERA. 47 



and moving the wheel-like cilia ; other filaments of greater length 

 stretch backwards into the cavity of the body, apparently attached to 

 the ventral integument, on the outer side of the principal longitudinal 

 retractor muscles. In Notommata clavulata Ehrenberg describes two 

 radiated ganglions in the neck {Jig. 20, d, d), superadded to the prin- 

 cipal cerebral ganglion connected with the rotatory muscle, and other 

 gangliforra bodies on each side, developed upon the long abdominal 

 nervous filaments. Besides these, other small enlargements are 

 figured as ganglions upon the transverse bands or " vascular circles " of 

 Ehrenberg, making altogether eight pairs of ganglions in this little 

 animalcule, which measures one-eighth of a line in length. With 

 regard to the ganglions on the so-called transverse vessels, both these 

 and the vessels bear a striking analogy to those transverse muscles 

 with a middle swelling, which Dr. Arthur Farre* has described and 

 figured in his Ciliobrachiate Polypes. The most satisfactory indica- 

 tion of the nervous system in a Rotifer appears to be that given by 

 Leydig in the Lacinularia socialis. It consists of two groups of four 

 spindle-shaped nucleated cells, the extremities of which are attenuated 

 and produced into fine (nervous) filaments. One group is situated 

 between the pharynx and ingluvies ; the other and more conspicuous 

 group is placed in the base of the tail. | 



The movements of the Rotifera are of a more varied character than 

 those in the Polygastria ; they sometimes dart swiftly forwards, at 

 others glide leisurely along, or, anchoring themselves by their little 

 terminal claspers, employ their ciliated paddle-wheels to create the 

 currents which prove so fatal to the minuter race of Infusories. The 

 Philodina creeps, like a leech, by the aid of a sucker at the mouth, 

 and another at the end of the tail. When the Rotifer has attached 

 itself to some fixed body by its hinder claspers, the vortices which it 

 occasions in the water are so directed as to draw the smaller Infusoria 

 and other particles of food towards the orifice of the infundibular 

 mouth. In some species this cavity is so large as to allow of a con- 

 siderable accumulation of food, as e.g., in the Stephatioceros {Jig. 

 22, c). In Lacinularia a pair of bifid salivary glands open into it. 



Having seized their prey, it is exposed in a second cavity or pharynx 

 to the destructive action of a complicated dental apparatus {Jg. 21, f). 

 This consists of two horny jaws, acting horizontally upon a median 

 piece, or anvil. The hard maxillae are each bent upon themselves at 

 a right, or, rather, acute angle ; the transverse or dental part, w^hich 

 beats upon the surface of the anvil, being divided into two or more 

 sharp spines. The muscles which work these dental hammers are 



* XXXV. p. 394., pl.xxi., fig. 13. f CLVIL, p. 452. t. xvii. 



