POLYZOA AND TUNIC ATA. 



159 



PLATE XXII. 



STRUCTURE OF LAGUNCULA REPENS (after Van Beneden). 



A, Polypide expanded; B, polypide retracted; c, another view of the same, with the visceral 

 apparatus in outline, that the manner in which it is doubled on itself, with the tentacular crown 

 and muscular system, maybe more distinctly seen: a, a, tentacula ; 6, pharynx ; c, pharyngeal 

 valve ; d, oesophagus; e, stomach ; /, its pyloric orifice ; g, cilia on its inner surface ; h, biliary fol- 

 licles lodged in its wall ; i, intestine; fc, particles of excrementitious matter; I, anal orifice; m, tes- 

 tis; n, ovary; o, ova lying loose in the peri-visceral cavity ; p, outlet for their discharge; q, sperma- 

 tozoa in the perivisceral cavity ; r, , t, u, v, w, x, muscles. 



p, Portion of the Lophophore more enlarged: a, a, t3ntacula; 6, 6, their internal canals; c, 

 their muscles; d, lophopnore; e^its retractor muscles. 



