ECHINOIDEA 



307 



to any large size, the horizontal diameter scarcely exceeding 

 70 mm. 



Fig. 175. — Paracentrotus lividus ; partly denuded. Slightly reduced. 

 (After Agassiz, Revision of Echini.) 



Fig. 176. — Globiferous pedicellaria and valve of tridentate pedicellaria 

 of Paracentrotus lividus. 1, x 3.*i ; 2, x 40. (After Th. Mortensen, 

 Echin. d. Mittelmeeres and " IngolJ" Ech., i.) 



The breeding season is in the summer months (in 

 the Mediterranean nearly throughout the year). The larva 

 (Fig. 177) has in the I. stage elongate, club-shaped, rather thorny 



