REPORT ON THE ASTEROIDEA. 



with adambulacral plates prominent. Pedicellarioe valvate, foraminate 

 or excavate ........... 



A. Marginal plates large and conspicuous ; with the axes of the plates of 

 the two series usually in parallel planes, 

 a. Apical plates decrescent. Abactinal skeleton with simple spini- 

 ferous spicules, with pseudo-paxillae, or true columnar 

 paxillse. Tegumentary developments usually spiniform. 



a. Marginal plates thin and lamelliform, naked, or covered only 



with membrane. Actinal areas paved with thin squami- 

 form plates covered with delicate membrane. Cribri- 

 form organs present. Adambulacral plates with a 

 simple marginal armature, uniserial .... 



b. Marginal plates thick and massive, covered with spines or 



papilla?. Actinal areas small, plates when present 

 covered with spines. No cribriform organs. Adam- 

 bulacral plates with a' complex armature, grouped or 

 in several series. 

 a. Proctuchous. Devoid of superambulacral plates. Adam- 

 bulacral plates large and not compressed. Pedi- 

 cellarise usually present ..... 



/3. Aproctuchous. With superambulacral plates. Adam- 

 bulacral plates short, and more or less compressed. 

 Pedicellarise rarely present ..... 

 b. Apical plates often increscent. Abactinal skeleton tessellate. Tegu- 

 mentary developments usually graniform. Actinal inter- 

 radial areas well developed. 



a. Abactinal skeleton tessellate, the plates often more or less 



tabulate, with co-ordinated granules simulating paxillse 



b. Abactinal skeleton stellato-reticulate. 



a. Abactinal plates with granules and tubercles. Actinal 



intermediate plates with large valvate pedicellarise 



/8. Abactinal plates with large conical spiniform tubercles. 



Actinal intermediate plates devoid of large valvate 



pedicellarise ....... 



e. Abactinal skeleton tessellate, the plates often irregular and 

 only partially contingent, covered with skin 

 B. Marginal plates comparatively small and inconspicuous ; with the axes 

 of the plates of the two series convergent and not in parallel 

 planes. Abactinal skeleton with lamelliform plates, imbricating, 

 notched on one side, with spines on the free margins. Spines on 

 the actinal intermediate plates. No pedicellarias 

 II. Marginal plates small and inconspicuous. Papulae not confined to the area 

 circumscribed by the supero-marginal plates, but often present between the 

 marginal plates and on the actinal surface. Ambulacral plates more or less 

 crowded and narrow. Actinostomial ring with ambulacral or adambula- 

 cral plates prominent. Pedicellarias pedunculate or sessile, not foraminate 

 A. Marginal plates small but persistent. Abactinal skeleton more or less 

 fully developed. Parambulacral and actinal intermediate plates 

 present ; one or both more or less fully represented. Interbra- 

 chial septa usually present. 



(ZOOL. CHAI.L. EXP. — PART LI. — 1888.) 



Order PHANEROZONIA. 



PorcellanasteridjE. 



Archasterid^e. 



ASTROPECTINID.E. 



Pentagoxasteri dm. 



Antheneid^e. 



Pentacerotid^:. 

 gymna8teriid.e. 



ASTERINID.E. 



Order CRYPTOZONIA. 



/ 



