Ichthydina.'] infusorial animalcules. 609 



Ehrenberg. It seldom swims, but mostly creeps. Fig. 356 exhibits 

 a fiiU-growu animalcule (ventral side). Found among Conferva and 

 Oscillatoria. Length l-440th to l-140th. 



Genus Chaetonotus. — The brushed Jish-Animalcules have hairs 

 upon their dorsal surface, possess a forked tail, but no eyes. Loco- 

 motion is performed by a double row of cilia upon the ventral 

 surface, forming a band-like rotatory organ. The nutritive organs 

 consist of a tubular mouth, probably provided with a cylinder of 

 teeth, a long thin oesophagus, and a long conical stomach (trachelo- 

 gastricum), upon whose upper thick end (in the large species) two 

 semi-globular glands are seen ; at certain periods, from one to three 

 large ova are formed posteriorly, but the ovarium in which they are 

 developed has not been directly observed ; male reproductive organs 

 unknown . They are sluggish in their movements, except in creeping ; 

 they rarely swim. 



C. maximus. — Body elongated, slightly constricted anteriorly, 

 turgid and obtusely three-lobed ; hairs upon the back short and 

 equal. From the latest observations, Ehrenberg states the mouth 

 to possess teeth, of which he has counted more than eight ; he once 

 saw the exclusion of ova immediately over the hinder foot-like tail. 

 It creeps but slowly. Size 1-2 16th to 1-1 20th. 



C. larus {Trichoda acarus anas et larus, M.) — Body elongated, 

 slightly constricted anteriorly, where it is turgid and obtusely tri- 

 angular ; the posterior hair on the dorsal surface is longest. 

 Ehrenberg has seen only one large ovum ; he states that the bodies 

 of those bearing ova were thick posteriorly, though, under other 

 circumstances, the head is broadest. It appears to have eight teeth. 

 Pancreatic glands unknown ; the dorsal hairs, which are arranged 

 in longitudinal rows, destroy the transparency of the body. Fig. 357 

 is a dorsal, and fig. 358 a side view. Ova l-3rd the length of the 

 body. Found in muddy water. Size l-720th. 



C. brevis. — Body ovato-oblong, slightly constricted near the 

 turgid front ; dorsal hairs few, the posterior longest ; ova small. 

 Size l-340th. 



As before stated, Dujardin places this genus Chaetonotus, together 

 with lehthydium, among the Infusoria {Polygastrica, Ehr.) ; in, 

 however, a sub-class of them, called symmetrical, along with Coleps 



