REPORT ON THE ASTEROIDEA. 



5G3 



b. Armature of the adambulacral plates consisting of two spines. Infero- 

 marginal plates with oblique combs of three spines . 



D. Asterias ophidion group : Abactinal plating forming a delicate, wide-meshed, 



quadrate network. Spinelets small, isolated, and few in number. 

 Pedicellaria; isolated ....... Sub-gen. 



a. IHplacanthid : Armature, of the adambulacral plates consisting of two 

 spines ........... 



E. Asterias miilleri group : Abactinal spinelets small and isolated. Papulae 



isolated or very few together ...... Sub-gen. 



a. Rays rather short and broad. Abactinal spines irregularly distributed . 



b. Rays elongate and narrow. Abactinal spines subregularly arranged 



in longitudinal lines ........ 



F. Asterias tenuispina group : Abactinal spinelets usually definitely arranged ; 



large and isolated, with thick wreaths of pedicellarise . Sub-gen. 



a. Heteractinid : With more than five rays. 



a. Monacanthid : Armature of the adambulacral plates consisting 

 of one spine. 



a. Infero-marginal plates with two spines. With one or 

 more intermediate series of abactinal spines between 

 the median radial and the marginal series, 

 i. With two abactinal intermediate series of spines. 

 Wreaths of pedicellarire flat and wide, not 

 raised. Large isolated forficiform pedicel- 

 lariae between. With eleven equal rays 

 ii. With one abactinal intermediate series of spines. 

 Wreaths of pedicellarias, thick and bushy, 

 raised. No forficiform pedicellarije between. 

 With seven to nine rays, usually unequal. 

 1. With long pointed spines, autacanthid (Bell) 

 |2: With short conical spines, typacanthid (Bell) 

 jS. Infero-marginal plates with one spine. No interme- 

 diate series of abactinal spines between the median 

 radial and the marginal series .... 



b. Pentactinid : Having five rays. 



a. Diplacanthid : Armature of the adambulacral plates consisting 

 of two spines. 

 a. With two or three complete intermediate series of abac- 

 tinal spines between the median radial and the 

 marginal series. No intermediate spinelets be- 

 tween the infero-marginal and the adambulacral 

 spines ........ 



/3. With one incomplete intermediate series of abactinal 

 spines between the median radial and the marginal 

 series. With an intermediate spinelet between 

 the infero-marginal and the adambulacral spines 

 /'. Monacanthid : Armature of the adambulacral plates consisting 

 of one spine. 

 a. Rays with vertical lateral walls. Median line of abac- 

 tinal spinelets straight. Intermediate spines few 

 and large ........ 



triremis. 



IIYDKASTERLA3. 



ophidion. 



Leftasterias. ' 

 . miilleri. 



, eompta. 



Stolasterias. 



gemmifera. 



tenuispina. 

 calamaria. 



volsellata. 



stichantha. 



i ustyla. 



glacialii 



