Dr. Gray on the Echinida. 201 



A. With angular pores at the junction of the plates. 

 1. Mespilia. 2. Microcyphus. 3. Salmacis. 4. Temnopleurus. 



B. Without any pores at the angles of the plates, 

 5. Echinus. 6. Psammechinus. 7. Heliocidaris. 



Fam. 6. Echinometrad^. 



Ambulacral area only half as wide as the interambulacral area ; 

 ambulacral pores in groups of four or more, forming an arched series 

 round the ambulacral tubercles. 



A. Body circular. 



1 . Strongylocentrotus. Spines equal, subulate, short. 



JB. Body oblong. 



2. Echinometra. Spines subulate, subequal. 



3. Holocentronotus. Spines of back elongate, subtriangular ; of 

 the oral side large, spathulate. 



4. Colobocentrotus. Spines of the back very short, truncated; of 

 the oral side spathulate. 



Dr. Gray described the following species, which he regards as new, 

 from the British Museum Collection. 



Genus Cidaris. 

 * Spines smooth or granular. 



1. Cidaris ornata. 



Depressed. Tubercles of interambulacral area rather distant; 

 spines lanceolate, subulate, depressed, white, red-ringed ; base with 

 series of small red spots and with regular longitudinal series of gra- 

 nules ; each side with one, and the upper surface of the base with two 

 series of white angular spines ; spinules white, with a central red 

 streak. — Hab. East Indian Seas. 



** Spines verticillate-spinose. 



2. Cidaris verticillata. 



Depressed. Interambulacral tubercles rather far apart ; spines of 

 upper surface rather elongate (about as long as the diameter of the 

 body), subulate, smooth ; some subulate at the top, others with 

 scattered conical spines, others obliquely truncated, cupped, and 

 spinose at the tip ; spines of lower surface shorter, cylindrical, trun- 

 cated, granular near the tip ; those of the oral surface much spotted, 

 truncated, compressed and largely granular near the end. 



Hab. ? 



3. Cidaris annulata. 



Orange. Rather depressed. Interambulacral tubercles of moderate 

 size, far apart ; spines elongate, subulate, tapering, red and white 

 ringed; suprabasal ring white; with longitudinal ridges. The ridges 

 of the lower half of the spines spinulose and with scattered larger 



