252 



CLASSIFICATION OF ANIMALS 



FIG. 142. Section through the arm and disc of a starfish. A, Anus; amp, 

 ampulla; cb, circular blood-vessel; civ, circular water canal; co, ccelom; co.e., 

 ccelomic epithelium; d.b., dermal branchiae; e, eye-spot; ect, ectoderm; ent, ento- 

 derm; /, ambulacral foot; g, ambulacral groove; h, hepatic caeca; i, intestine; 

 i.e., intestinal caeca; mes, mesoderm; mo, mouth; mp, madreporic body; nr, 

 nerve ring; os, ossicles; rn, radial nerve; rb, radial blood-vessel; rp, genital pore; 

 rw, radial water canal; sc, stone canal; sp, spine. (From Galloway.) 



d. b. 



r.p 



---z 



FIG. 143. Cross section of the arm of a starfish, ar, Ambulacral rafter; ov, 

 ovary containing ova. Other lettering as in preceding figure. (From 

 Galloway. ) 



