302 



ROTIFERA. 



which special muscles are inserted. Such are found in Triarthra, 

 Polyarthra, etc. In one family the Pedalionidae the body pos- 

 sesses hollow appendages containing muscles, and recalling very 

 closely the limbs of Arthropoda (Fig. 246). 



The body-wall consists of a cuticle with a subjacent protoplasmic 

 layer with scattered nuclei, but without cell-limits. This doubtless 

 represents the ectoderm. There does not appear to be any con- 



FIG. 246. Pedalion mirum, side view (from Perrier, 

 after Gosse). g eyes ; c velum ; m, m', m" mus- 

 cular bands ; v ventral appendage ; d dorsal appen- 

 dage ; 1,1' lateral appendages. 



FIG. 247. Melicerta ringens (after 

 Leuckart and Nitsch, modified 

 from Ehrenberg and Joliet). 

 showing the tube formed of 

 pellets cemented together. 

 mouth ; Ph pharynx ; L ciliated 

 lobe overhanging W the cili- 

 ated cup ; Dr cement gland ; 

 M stomach ; T tentacle ; B 

 trochal disc. 



tinuous muscular layer in the body-wall, but there may be a small 

 amount of connective tissue, inasmuch as connective tissue fibres 

 can be seen passing between the various organs across the body- 

 cavity. 



The cuticle is sometimes soft and thin, sometimes hardened into 

 a kind of shell, called the lorica (the Ploima) ; there are sometimes 

 joints in it, which give the body a segmented appearance. The 



