182 



COLLEGE ZOOLOGY 



Two coiled tubes {nph), which 

 give off a number of ciliated 

 lobules (fl.c), and enter a 

 bladder (c.v), constitute the ex- 

 cretory system. The bladder con- 

 tracts at intervals, forcing the 

 contents out of the anus. Since 

 the amount of fluid expelled by 

 the bladder is very large, it is 

 probable that respiration is also 

 a function of this organ, the 

 oxygen being taken into the 

 animal with the water which 

 diffuses through the body-wall, 



Fig. 12: -Two species of Ro- and the carbonic acid being cast 

 tifera. A, Philodina. B, Hyda- ut with the excretory fluid. 



tina. (From Parker and Haswell, ™, , , ., 



after Hudson and Gosse.) The body-Cavity IS not a true 



ccelom. 

 The sexes of rotifers are separate. The female possesses an 

 ovary (Fig. 123, ovy) in which the eggs arise, a yolk-gland (vt) 

 which supplies the eggs with yolk, and an oviduct (ovd) which 



flc 



d.eb . 



Fig. 123. — Diagram showing the anatomy of a Rotifer. 

 a, anus; br, brain; c 1 , preoral, and c 2 , postoral circlet of cilia ;\ 

 c.gl, cement gland; cl, cloaca; d.ep, dermic epithelium; d.f, dorsal 

 feeler; e, eye; fl.c, flame-cells; inl, intestine; m, muscles; mth, mouth; 

 nph, nephridial tube; ov, ovum; ovd, oviduct; ovy, germarium; ph, pharynx: 

 st, stomach; vt, vitellarium. (From Parker and Haswell.) 



