I 7 2 



MANUAL OF ZOOLOGY 

 Ap 



SECT. 





FIG. 95. Corona of sea-urchin with the spines removed to show the arrangement 

 of the plates, lateral view. Amb, ambulacra! zone with its perforated plates; 

 Ap, apical (aboral) pole; Int. amb, inter-ambulacral zones. (From Bronn's 

 Thierreich.) 



sharp tooth. The points of these five teeth can be seen 

 through the opening of the mouth. The enteric canal has 



no radiating coeca. The five 

 ducts of the reproductive or- 

 gans open on five ossicles, the 

 genital plates (Fig. 96, geri), 

 which with five smaller ocu- 

 lar plates (oc) each bearing 

 a rudimentary eye, form a 

 complete ring round the 

 space (peripr) at the anal 

 pole, in the middle of which 



of a sea-urchin. amb, ambulacral ,1 



zones; gen, genital plates; int. amb, IS the attUS ; a 



inter-ambulacral zones; madr, madre- orv , < ,l fTOrr ,,,4., i/ 4 



porite; oc, ocular plates; peripr, peri- 1S amalgamated 



proct. (After Leuckart.) the genital platCS. 



rvf 

 Ot 



