ECHINOIDEA 313 



1. Strong ylocentrotus drobachiensis (O. Fr. Miiller). (Fig. 181.) 



(Syn. Echinus neglectus Lamk. ; Toxopneustes drobachiensis (0. F. 

 Miill.) ; Toxopn. pallidus G. 0. Sars ; Toxopn. pictus 

 Norman ; Strongyloc. granular is (Say)-) 



Test low, but arched, not flattened ; it is rather closely set 

 with tubercles, among which the primaries form distinct vertical 

 series. In larger specimens also the secondary tubercles form 

 fairly distinct vertical series. Usually 5-6 pore pairs in each 

 ambulacral plate. As a rule two of the ocular plates reach the 

 periproct. Spines of rather uniform length, the primaries no't 



Fig. 181. — Denuded test of Strongylocentrotus drobachiensis, seen from 

 above. Nat. size. (From Danmark's Fauna.) 



very conspicuous. No spines on the buccal plates. Globiferous 

 pedicellarise fairly large and conspicuous, usually with numerous 

 spicules arranged in a band along the sides of the valves 

 (Fig. 143, 6). Tridentate pedicellariae usually with rather 

 broad, leaf-shaped valves. Colour of test mostly greenish- 

 brown, the spines greenish or reddish, sometimes violet, often 

 with whitish point. Reaches a size of ca. 80 mm. horizontal 

 diameter. 



The breeding season in the early sj^ring (perhaps also in the 

 winter-time). The larva has in the I. stage elongate, club- 

 shaped body-rods (Fig. 148, 4). In the II. stage it has 

 epaulettes at the base of the postoral and postero-dorsal arms, 

 and a pair at the posterior end of the body, forming almost a 

 closed ring. (Probably the larva designated as Echinopluteiis 

 coronatus Mrtsn. belongs here.) Otherwise this larva is very 



