REPORT ON THE ASTEROIDEA. 



389 



Synopsis of the Species o/ - Asterina, herein mentioned. 



A. Actinal intermediate plates with few spines (two to five), arranged in single series. 



a. Actinal intermediate plates with one spine only on the inner part of the 



interradial area. 



a. Actinal intermediate plates with one spine on the outer plates. 



Adambulacral plates with one spine on the actinal surface. 



a. Actinal intermediate plates with one spine on all plates. 

 Abactinal plates with granules arranged in semicircles. 

 Five rays. Spines on actinal intermediate plates short 

 and conical ........ regularis. 



/3. Actinal intermediate plates on the inner part of the inter- 

 radial area devoid of spines. Abactinal plates with 

 granules not arranged in semicircles .... exigua. 



b. Actinal intermediate plates with two spines on the outer plates. 



Adambulacral plates with two spines on the actinal surface. 

 Abactinal plates well-spinulated or granulate. Six rays . . gunnii. 



b. Actinal intermediate plates with two to five spines on each plate. 



a. Adambulacral plates with two or three spines on the actinal surface. 



Abactinal plates well spinulated. 



a. Actinal intermediate plates with more than two spines. 

 Adambulacral plates with four or five spinelets in the 

 furrow series. Actinal intermediate plates with five 

 spines in line, pointed ...... pectinifera. 



b. Adambulacral plates with more than three spines on the actinal 



surface. Abactinal plates almost naked, spinelets simply mar- 

 ginal and inconspicuous. 



a. Actinal intermediate plates with three or four long delicate 

 spines, united by membrane, not regularly in line. 

 Adambulacral plates with four or five spines on the 

 furrow margin and three or four on the actinal surface . folium. 

 ,6. Actinal intermediate plates with two to four short, small, 

 conical spinelets, not united. Adambulacral plates with 

 five to seven spines on the furrow series and four or 

 five on the actinal surface cepheus. 



B. Actinal intermediate plates with numerous (eight to sixteen) spines, forming a 



double or triple line ........... penicillaris. 



Chorology of the Genus Asterina. 



a. Geographical distribution : — 



Atlantic : Eleven species between the parallels of 60° N. and 40° S. 



Asterina gibbosa, off the European and North African coasts, 

 and in the Mediterranean. Asterina gibbosa is also reputed to 

 extend into the Indian Ocean and Eastern Archipelago, but the 

 occurrence of this species out of the Atlantic needs verification, 



