34 



LECTURE III. 



use. These appendages are longer than the body in some species, as 

 the Notommata Tigris : their sheath is much elongated and slightly 

 anniilated in the Brachioni : it is telescopiform in Scaridiiim : both 

 claspers and sheath are wanting only in the AimrcEus. The integument 

 of the body is smooth, and never ciliated : although the parasitic jointed 

 fibres of HygrocrociSi which attach themselves sometimes to the in- 

 tegument of the larger species, as ISotommata centrura, give it that ap- 

 pearance. The PolgarthrcB have long jointed filaments, like the rays 

 of a fish's fin, attached to the sides of the body. 



Not any of the species are known to secrete a silicious shell ; but 

 many of them are provided with a transparent gelatinous case, into 

 which they can contract their bodies ; thus off'ering another analogy 

 to the Ciliobrachiate Polypes, and also to the bivalve-sheathed Ento- 

 mostraca. The loricate genera are Noteus, Anurcea, Brachionus^ and 

 Pterodina. In all the species the shell is a cylinder or case {testula), 

 not a mere shield (^scutelluni). 



Horn-like processes project from the front margin of the shell in 

 some species of Brachionus, and from both front and back margins in 

 other species. In some Notei and Anurcece the shell is ornamented 

 by large pentagonal or hexagonal groups of granules. 



The cephalic cilia are aggregated into from two to five groups, upon 

 lobes (Jig- 15, «.), which sometimes are developed into short tentacular 

 processes, with a verticillate arrangement of cilia, as mStephanoceros, 

 These lobes or processes Ehrenberg regards as muscular. The 



movements of the ciliated quasi- 

 wheels are under the control of 

 the will. They can be instantly 

 arrested, the whole apparatus 

 drawn out of sight, again pro- 

 truded, and as instantly set in 

 motion. The muscles which pro- 

 trude and retract of the ciliated 

 lobes, which bend and modify the 

 form of the body, and which 

 throw out, attach, or heave in the 

 anal anchors, are developed in 

 the form of distinct fibrous fas- 

 ciculi. You perceive in this dia- 

 gram, for example (fig. 15.), the 

 Notommata. rctractors of the oral cilia and of 



the anal forceps ; the long and narrow longitudinal muscles (Z>, 6), 

 which shorten the whole body ; and their antagonists the transverse 



