SHALLOW-WATER STARFISHES 27 



Family ASTERIIDJE Gray (emended). 



Asteriida: GRAY, Ann. Mag. Nat. Hist., vi, p. 178, 1840; Synopsis, p. I, 1866. 



Perrier, Revis. Stell., Arch. Zool. Exper. et Gen., iv, p. 302, 1875; Mem. 



Etoiles de Mer, pp. 167, 198, 1876. Viguier, Squelette des Stellerides, pp. 



93, 99, pl- v, figs, i-io, 11-12, 1878. 

 Asteriida! (emended) + Stichasterida; SLADEN, Voyage Chall., xxx, pp. 430, 



560, 1889. Perrier, Exp. Trav. et Talisman, pp. 43, 105, 107, 128, 1894; 



Contrib. 1'etude des Stellerides Atlan. Nord, pp. 25, 31, 1896. 



Rays five to twenty or more, but most frequently five or six. 

 Madreporic plate generally single in five-rayed and six-rayed forms, 

 but often two or more in those with a variable number of rays. 

 Dorsal and actinal plates various in form and arrangement. Odonto- 

 phore usually formed of a single piece. Oral ambulacral plates 

 elongated; those along the grooves become very short and com- 

 pressed. Papulae occur both on the actinal and dorsal sides. Ambu- 

 lacral feet usually crowded in four rows, sometimes more. Pedicel- 

 lariae of two kinds are present. Dorsal ossicles generally bear 

 spines or spinules, various in size and kind, and sometimes granules. 

 They are never true paxillae. 



The mouth is large; the stomach saccular and evertible; intestine 

 rudimentary or abortive. A subcentral, dorsal pore (nephridial pore) 

 is present, through which is discharged the secretion of the branched 

 or lobular " rectal " or nephridial glands, which are usually unequal 

 and often but two or three in number. This pore is usually called the 

 " anal pore," but rarely, if ever, functions as an anus in this family. 

 The intestine is nearly or quite abortive, in most cases. 



I. MORPHOLOGY OF THE OSSICLES. 



Aside from the ambulacral and adambulacral plates, the skeleton 

 of the rays consists of five fundamental or primary rows of ossicles, 

 viz., the median dorsal or carinals; the two superomarginals; and the 

 two inferomarginals. The latter may or may not be confined to the 

 ventral side. (See fig. I, i.) 



The ossicles of adjacent rows may be articulated directly by their 

 lobes, or either large or small, simple connecting ossicles may inter- 

 vene. 



This simple or primitive type of skeleton is found in Heterasterias 

 volsellata (Sla.), and in a few other species, especially when young. 



In most cases more or less numerous ossicles or rows of ossicles 

 are interpolated during growth between the five primary rows, either 

 above or below, or between the marginals, thus giving rise to many 



