SHALLOW-WATER STARFISHES 49 



dorsal pedicellariae, not found in northern polyactinoplacid types. Its 

 principal dorsal plates are in regular radial rows. 



This suggests an independent line of development, and hence the 

 group may well receive a distinctive name. C. tomidata (Sla.), the 

 type, was from Chile, in 45 fathoms. 



Somewhat similar, large, unguiculate or felipedal pedicellariae 

 occur on Stichaster polygrammus Sla., off Patagonia ; S. felipes Sla., 

 South Africa; Stolasterias volsellata Sla., Philippines; Coronaster 

 briar eus (V.), Atlantic, and some other species. 1 In these they are 

 not so sessile and rigidly erect as in Pisaster. Each of those species 

 named is now referred to a distinct genus. 



E. TABLE OF PRINCIPAL GENERA OF ASTERIIN^ WITH REGU- 

 LAR LONGITUDINAL ROWS OF DORSAL PLATES AND 

 SPINES. 



I. NOT MORE THAN ONE ROW OF EVIDENT ACTINAL (PERACTINAL) 

 PLATES, MONACTINOPLACID OR ANACTINOPLACID. 



A. Monacanthid, or nearly so. 



B. Rays slender, variable, mostly six to eleven ; often more than two madre- 



poric plates when adult; usually autotomous. 



C. One (often incomplete) row of actinal plates, closely united to adambu- 



lacrals, and usually bearing a simple row of spines (monactino- 

 placid). Major pedicellariae large, compressed, ovate or pointed. 

 Usually three or five rows of dorsal plates and spines, 

 a. Peractinal spines usually present in the adult. 



Coscinasterias Ver. Type, C. nturicata Ver. 

 aa. Peractinal spines mostly absent. 



Section Stolasterias (Sla.), restr. Type, C. (S.) tenuispina. 

 CC. No visible actinal plates, the inferomarginals joining the adambulacrals 

 (anactinoplacid). Only one row of dorsal plates the median 

 radials. Some large, unguiculate, dermal major pedicellariae; some 

 of the plates may be diplacanthid. 

 Heterasterias Ver., nov. Type, H. volsellata (Sla.) 



BB. Rays five or six, stout. Three or five rows of strong dorsal plates and 

 spines. No interactinal plates with spines. Usually but one madre- 

 poric plate ; rarely two. 



Marthasterias Jullien. Type, M. glacialis (Mull.). 

 AA. Adambulacral plates mostly diplacanthid. 



D. No evident interactinal plates that bear spines; if present, rudimentary. 



a. Five or more rows of stout dorsal plates and spines when adult. Major 



pedicellariae not felipedal. 

 Distolasterias Per. Type, D. stichantha (Sla.). 



1 They often resemble, more or less, a pair of miniature clasped hands with 

 fingers interlocked or two catspaws with claws protruded and interlocking, 

 and hence they may be called felipedal. The name of 5. felipes Sla. refers 

 to this feature. 



