or THE KOTATOEIA. 405 



and Pliilodiyia, and also on the shorter foot-process of Dlnocharis. These 

 styles are moveable and flexible, and occur in a single pair or in two or three 

 paii's ; Ehrenberg gave to such, when short and not rigid, the name of ' toes, 

 and distinguished the prolongation on each side of the posterior border of the 

 shding-joints, seen in Rotifer, Actinurus, and Callid'ma, as ' hom-like pro- 

 cesses.' In Scaridium (XXXYIII. 22) and Dlnocharis, the foot, though 

 jointed, seems not to be retractile. 



The pseudopodium diifers much in its length and mode of termination. 

 Where the articulated segments are few and small, the foot, if terminated by 

 styles, oftentimes acquires a great length. In some species the terminal 

 styles are three in number — e. g. Actinurus, Philodina Neptunius, DinochariSf 

 and in some Stephanoijes ; and more frequently the central style is shortest. 

 Two teiminal styles are more common. Illustrations are found in Furctdariay 

 Scaridium, Distemma, &c. A foot ending in a paii' of styles is said by Ehren- 

 berg to be ' forked ' {furcate). 



In numerous species the styles have much rigidity, and are greatly elon- 

 gated ; in such instances they are known as styliform setae, or simply ' setce.' 

 Two such terminate the trunk in Notommata longiseta, N. cequalis, and in 

 N. Felis — in the last-named they are also curved backwards, — whilst but one 

 is produced from the body in Monocerca (XXXYIII. 399), Mastigocerca 

 (XXXIV. 438-440), and in Ratulus ; in the last, moreover, the base of the 

 setae is surrounded by stiff hairs. 



Another very common termination of the foot is by a pair of short thick 

 flaps, moveable on their base, and named ' pincers,' or ' pincer-like processes.* 

 Such are seen in Brachionus, Hydatina (XL. 1), Enteroplea (XL. 2), DigleTia, 

 Eosphora, Noteus (XXXVIII. 2b), and in several Notommatce (XXXVIII. 5, 

 25, 26). 



AU the preceding varieties of the pseudopodium are modifications of the 

 articulated telescopic type, and associated with a tolerably fii-m cuticle. But 

 there is yet another type, in which no articulated segments occur, and which, 

 from the softness of its tissues, is thro^vTi into wrinkles or folds during con- 

 traction. Illustrations of this are found in aU the urceolate genera of the 

 Rotatoria, viz. in Coywchilus, Lacinularia, Melicerta, Tuhicolaria, Steplianoceros 

 (XXXVIII. 1, 17, 19), &c., and, besides these, in the free Megalotroclicea 

 (XXXII. 374-378) and in Pterodina (XXXV. 502-504). In the attached 

 genera especially, this form of pseudopodium rather merits the name of 

 ^pedicle ' or footstalk. In Pterodina the cylindrical foot-process is trumpet- 

 shaped, and discoid at its free extremity, which is supposed to act hke a 

 sucker. A suctorial end to the pedicle is likewise presumed to exist in some 

 or aU of the fixed genera. 



Cilia have been discovered on the extremity of the pseudopodium of Ptero- 

 dina and Tuhicolaria, and on that of MegalotrocTia, Lacimdaria (XXXVII. 

 10), and Brachionus in the young or immature state. 



Lastly, a pseudopodium is absent in Anurcea, Asplanchna (XXXVI. 9 ; 

 XXXVII. 29-32), Polyarthra, Triarthra (XXXVIII. 30), and Ascomorpha. 



The observations of these and other particulars concerning the pseudopo- 

 dium, its presence or absence, its structure, its length relatively to the body, 

 and to its own processes, supplies valuable characters in the systematic distri- 

 bution of the Rotatoria ; and the details so derived furnish the fundamental 

 divisions of the classification proposed by Ley dig {see Classification). 



The foot-like process is essentially a muscular organ ; it contains no viscera, 

 but in highly-developed forms some small bodies supposed to be glands, and 

 in some examples certain vesicular spaces supposed by some to be ganglia, by 

 others, vacuolar thickenings of the connective tissue (XXXVII. 17 n). The 



