482 



COMPARATIVE ANATOMY 



CHAP. 



Fin. 384. Radial-interradial section in the direction of the principal axis through the 

 calyx of Pentacrinus decorus (after P. H. Carpenter), left half radial, right interradial, dia- 

 grammatic. In many respects the figure is obsolete and incorrect. The most noteworthy points 

 are emphasised by special type in the following lettering, so, Subambulacral plates ; ?, radial 

 nerve trunk (hatched) ; /v, radial pseudohivmal canal (black) ; ra, radial canal of the water vascular 

 system (dotted); cl], brachial crelom ; pi, spongy organ of the blood vascular system; an, circular 

 canal of the water vascular system ; n, mouth ; an (to the right), nerve ring ; av, blood vascular 

 ring? pseudolni-mal ring?; mi (to the left), anus; re, rectum; in, plates of the interambulacral 

 areas ; jm, calyx pores ; cl, the coelom, traversed by a spongy network ; it, intestinal coils 

 (cut through); gp, axial organ; in.ii, muscles; im, nerve commissure between the axial trunks; 

 IHI, basal ; n; cirrus canal ; en, cirrus nerve ; ch, chambered sinus, with the centre of the apical 

 nervous system; >; radial plate; r } , <._,, first and second costal; iii, distichal ; .//, syzygial 

 suture ; gv, genital canal ; ai-n, apical nerve trunk of the arm. 



