RAYS AND BILATERAL SYMMETRY 27 1 



ABBREVIATIONS USED IN PLATES XIII AND XIV. 



A. Sixth ray. 



a. Anus. 



adam.p. Adambulacral plate. 



amb. Ambulacral foot of old ray. 



amb.' + -+'^''"''' Ambulacral feet of new ray. 



amb.m. Muscle fibers of new ambulacral foot. 



amp^. Ampulla of new ray. 



a.p.c. (See o.p.c. ) 



cce. Body coelom. 



coe'. Ccelom of new ray. 



coe.e. Coelomic epithelium. 



c.w.r. Point of closure of hydrocoel ring. 



f.sp. Furrow spine. 



ect. Ectoderm. 



i.p.c. Inner perihsemal ring canal. 



Ix, 1x1, lx'2, Ix^, etc. Accessory rays of left side. 



o.p.c. Outer perihaemal ring canal. 



m. Mouth. 



mp. Madreporite. 



mr.s. Marginal dorsal spines. 



m.s. Median dorsal spines. 



m.amp. Mouth of pocket of new ray. 



n.r. Nerve ring. 



per. Peristome. 



p.s. Septum between perihsemal ring canals. 



p.c. Radial perihaemal canals. 



r.g. Racemose glands. 



r.p. Pocket of new ray. 



r.n. Radial nerve. 



r.w.v^. Supposed beginning of radial water canal. 



rx, rx^, rx^, rx^, etc. Accessory rays of right side. 



s.c Stone canal. 



ten. Terminal tentacle of new ray. 



w.r.c. (figs. 9, II and 12). Water ring canal. 



w.v.r. (fig. 13). Water ring canal. 



X. Edge of ectodermal lip of pocket of new ray. 



y. Point at which body ccelom evaginates to produce coelom of new ray. 



I, II, III, IV, V . The original five rays of the five-rayed star. 



