152 THE PROCEEDINGS OF THE LINNEAN SOCIETY 



Genus 2. — Stephanocidaris, A. Agassiz, 1863. 



Test exceedingly thin, abactinal system large, thin, packed with 

 milliares, moveable ; primary tubercles more numerous than last 

 genus. 



Stephanoctdaris bispinosa, Lamarck. Primary spines flattened, 

 tapering with very marked serrated edges, and smaller spines 

 along medium line of shaft. Primary tubercles small, mammary 

 boss little prominent, auricles very high and thin. 



Said to occur in Australia, on very good authority, but I have 

 never met with a specimen. 



G-enus 3. — Goniocidaris, Desor, 1846 



Test frequently higher than broad, coronal plates more numerous 

 than in any other genus of the family. Tubercles perforate, with 

 a smooth base. A. narrowest of the family. Poriferous zone 

 almost as broad as the medium A. region. Medium A. and I. 

 areas bare, sutures of plates sunk, forming deep zigzag vertical 

 sutures, with pits at the angle of two plates. Spines cylindrical, 

 covered with thorny spines pointing irregularly outwards, spread- 

 ing out, frequently cupped at the extremity. 



Goniocidaris geranioides, Lamarck. Test high, thick, as 

 many as ten primary tubercles. Scrobicular circle small, circular, 

 well denned by a close row of secondary tubercles. Poriferous zones 

 narrow, with high ridge separating the pairs of pores. Primary 

 spines fluted, swelling near base, cupped at the top ; near upper 

 part of spine, fluting often broken up into disconnected lamellae, 

 or irregular rugose projections. 



Common. Darnley Island, New Guinea, Endeavour River, 

 " Chevert Expedition." 



Goniocidaris tubaria, Lamarck. Test somewhat flattened. 

 Eight primary tubercles. Scrobicular circle elliptical, mammary 

 boss small, not prominent. Differs strikingly from the pre- 

 ceeding species in the structure of the primary spines, which are 

 somewhat swelling at the base, tapering, cupuliform. Shaft 

 ornamented by irregular longitudinal rows of small flattened 

 disconnected pointed lamella^ forming diminutive spines. 



