484 



COMI'ABATIVE ANATOMY 



CHAP. 



Ill the EcMnmtenila' and Asierinidce, the coirimon tube swells into 

 a large sac. 



At the point where the stomachal sac narrows to form the short 



Fig. 385.— Alimentary canal and genital organs of an Asteroid, diagrammatic. 1, Brachial 

 'liverticula of the stomach ; 2, gonads ; 3, base of the ^onad, which corresponds witli its aperture ; 

 4, stomachal sac ; .0, anus ; 0, rectal diverticula ; 7, apical circular sinus and trunl^ ; 8, one of the 

 ten radial sinuses and trunks running from this Latter to the gonads ; 9, stone can.al in the axial 

 sinus ; 10, madreporitt'. 



rectum, i.e. high up in the apex of the disc, it is once more provided 

 with diverticula. These rectal diverticula, whose number, arrange- 



