ECHINOIDEA 



311 



the case in the Arbacia larva (Fig. 165). A broad epaulette is 

 found at the base of each postoral and postero-dorsal arm 



Fig. 179. — Globiferous peclicellaria (1), valve of tridentate pedicellaria (2), 

 and spicules from globiferous pedicellarise (3) of Sphcer echinus granu- 

 Inris. 1, x27; 2, x 40 ; 3, x 500. (After Th. Mortensen, Ech. d. 

 Mittelmeeres (1) and " Ingolf Ech., i. (2-3). 



Fig. 180. — -L,arva oi Sphcerechinus granularis. (After Joh. Midler, \'II. Abh 

 iiber Echinod.-larven ; slightly corrected.) 



(Fig. 180). Rate of growth of the sea-urchin unknown, but it 

 may be already sexually mature at a size of 8 mm. horizontal 



