lll/datinaca.'\ INFUSOEIAL ANIMALCULES. 643 



tlie vibratile lining membrane of tlie anterior portion of tlie alimentary 



canal. Found amongst Conferva. Length l-160tli. 



DiGLEKA catellina {Cercaria catelUna, Vorticella larva, M.) — Body 



oblong, short, ends truncated; foot short, and inferior. The small size of 



this animalcule is imfavom*able for observing its internal organization. 



It is found at all seasons of the year in open water, and in infusions 



covered with a gTccn pellicle, which is often filled with its eggs; 



these, when rapidly developed by genial weather, cause a millcy 



turbidity in the water. Length l-3C0tli. 



D. conura. — Eody ovato-oblong, straightly truncated in front, and 



gradually attenuated to a conical foot. Found amongst Oscillatoria. 



Length 1- 144th. 



D. capitata. — Body oblong, conical, obliquely truncated, and dilated 



in front ; toes long, without apparent base, or foot. This animalcule 



feeds upon Chlamtdomonas and ]\^aviculce. Length l-300th. 



D. caiidata ( Vorticella furcata, M.) — Body elongated, conical, 



obliquely truncated anteriorly, but not dilated ; foot distinct, short ; 

 toes long. Found in green water. Length 1 -200th. 



D. (?) hirajMs (Gosse.) — Body oblong, the head and abdomen 

 gently sweEing ; toes long, slender, straight, and perfectly even in 

 thickness; eyes placed close together, frontally; jaws protrusilc ; 

 alimentary canal very large, projecting behind and above the gizzard, 

 alwaj'-s filled with green matter. Length including toes 1-11 0th. 



Genus Teiakthra. TJie three-learded Rotatoria possess two frontal 

 eyes, a simple styliform foot, and beard, or breast fins. Beside the 

 rotaiy organ, internal band-like muscles are observed, and two 

 bristles, or fins, which assist in leaping, as in Polyarthra. The nu- 

 tritive apparatus consists of an oesophageal head, having four muscles, 

 and two double-toothed jaws, as in Rotifer ; an oesophageal tube, 

 long in one species, short in the other ; and a simple, conical, or 

 constricted alimentary canal, with two spherical glands. Both 

 ovarium and contractile vesicles are seen ; the eggs, when expelled, 

 remain attached by threads. A vascular system is unknowTi, — the 

 nervous is indicated by the two red eyes, placed upon ganglia. 

 Both species often produce a milky turbid appearance in the water, 

 when developed in masses. 



T. longiseta {TricJmla, M.) — E}cs distant, the cii-rhi or beards, 



