394 DESCRIPTION OF [Rotatoria. 



FAMILY XXIX. PHILODINAEA. 



This family comprehends Rotatorial Animalcules devoid 

 of lorica, but possessing two simple rotatory organs, re- 

 sembling wheels. The body of most species is worm-like, 

 or spindle-shaped (fusiform). Portions of the body can be 

 thrust in and out, like the tubes of a telescope slide, within 

 each other; this is produced by a sort of false joint, caused 

 by a peculiar insertion of the muscles. In all the species 

 the foot is furcated, and in Callidina, Rotifer, Actinurus, 

 and Philodina, it is provided with soft processes, resembling, 

 in shape, horns, near the false joints, as in the genus 

 Dinocharis (Jig. 455^. Muscles are seen in the genera 

 just named. The nutritive apparatus consists of an oeso- 

 phagal head, with two jaws ; in three genera they are 

 double-toothed (zygogomphia) ; in two the teeth are in 

 rows (lochogomphia). In the four principal genera the 

 alimentary canal is filiform; it is furnished with a bladder- 

 like expansion at its commencement (trachelocystea), and 

 surrounded by a turbid cellular or glandular mass. In one 

 genus the alimentary canal is conical (coelogastrica), and, 

 in the two African genera, is unknown. In four genera the 

 intestine has glands; in a like number the propagative 

 system is hermaphroditic, an ovarium, male glands, and con- 

 tractile vesicle being present ; the latter only, however, in 

 Rotifer and Philodina, which, together with Actinurus, are 

 sometimes viviparous. In Rotifer and Philodina portions 

 of a vascular system are visible, in the form of from nine 

 to twelve transverse vessels ; these, as also Actinurus and 

 Monolabis, have spur-like respiratory tubes. In thirteen 



