46 



ASTEROIDEA. 



Second Family. 

 Two rows of tentacula in the ambulacra! avenues. With a vent. 



2 Genus. — Echinaster, M. and T. = Pentadacti/losaster, Linck. 



Rays long, conical, or cylindrical ; the skin supported on a network of calcareous pieces, 

 from which longer or shorter spines proceed, sometimes alone or set close together. Skin 

 between the spines nakedj with many tentacule-pores. Vent subcentral. 



3. Genus. — Solaster, Forbes. 



Fig. 21. 



A. B. 



Portion of a ray of Solaster papposa, Linn. A, the under ; 

 U, the upper surface. 



Body stellate, raultiradiate ; rays 

 moderately long, and covered with fas- 

 ciculated spines; skin between the 

 spines naked, with many pores ; no 

 pedicellariae ; vent central. 



4, Genus. — Chjeta§ter, M. and T. 



Rays narrow and elongated, covered with plates which carry on their summits fascicu- 

 lated spines, single pores between the plates ; vent subcentral. 



5. Genus. — Ophidi aster, Agass. = Linchia., Nardo (pars). 



Fig. 22. 



Section of a ray of Ophidiaster, with the inter-ambulacral plates. 



R,ays cylindrical or conical, 

 everywhere covered with granular 

 plates ; many pores between the 

 plates, which are likewise surround- 

 ed by granules ; no pedicellariae ; 

 vent central. 



6. (7r'^««.— Scytaster, M. and T. = Pentadacti/losaster, Linck.; Li7ickia, Nardo. 



Rays elongated ; body stellate, everywhere covered with granular plates, which are 

 arranged on the margins in two rows ; the space between the plates likewise granulated. 

 The pores between the plates single. No pedicellariae ; vent subcentral. 



