SHALLOW-WATER STARFISHES 1OI 



Genus Asterias Linne (restricted). See page 43. 



Asterias (pars) LINNE, Syst. Nat., ed. x, 1758; ed. xn, p. 1098, 1766. Gray 

 (restr., pars), 1840; Synopsis, p. i, 1866. Perrier (pars), Revis. Stell., 

 op. cit, iv, p. 302, 1875. Bell, System. Arrangement, Proc. Zool. Soc. 

 London, 1881, p. 492. 



Stellonia (pars) NARDO, Oken's Isis, p. 716, 1834. Agassiz, Prod., p. 191, 1835.' 



V raster (pars) FORBES, Mem. Wernerian Soc., vni, p. 114, 1839. 



Asteracanthion (pars) MULLER and TROSCHEL, Monatsb. Akad. wiss., Berlin, 

 p. 102, 1840; Syst. Ast, p. 14, 1842. A. Agassiz, North Amer. Starfishes, 

 p. 94, 1877 (structure). 



Asterias NORMAN, Ann. and Mag. Nat. Hist., ser. 3, xv, p. 126, 1865. 



Asterias (pars) SLADEN, Voy. Chall., xxx, p. 560, 1889. Perrier, Exp. Trav. 

 et Talism., p. 108, 1894. 



Diplasterias (pars) PERRIER, Exp. Trav. et Talism., p. 108, 1894. 



As here restricted, this genus is characterized by having the larger 

 dorsal ossicles well developed, with three or four lobes, united in a 

 reticulated or irregular manner, and with oblong transverse ossicles, 

 uniting the longitudinal series, and thus leaving relatively large, 

 irregular papular areas, from which arise clusters of few or numer- 

 ous small papulae. The median radial dorsal ossicles usually form a 

 distinct row, with spines more prominent than the others. The 

 interactinal plates usually consist of only one or two (sometimes 

 three) rows, including the synactinal or connective plates, all of 

 which are usually so united as to leave papular areas. (See p. 33 

 above.) 



The adambulacral spines may stand either one or two to a plate, 

 but very commonly they are alternately or irregularly one and two. 

 The actinal and lower marginal spines usually form three to five 

 rows, which are longer and larger than the dorsal spines, and in 

 large specimens often stand two or three on one plate. The supero- 

 marginal or lateral spines generally form a distinct row, leaving a 

 lateral naked lane or " channel " between it and the lower marginals ; 

 a small series of ossicles may sometimes be interpolated in this area, 

 at the bases of the arms. The dorsal spines may be of almost any 

 shape, but are generally shorter than the marginals and actinals 

 and often different in form. The spines are generally surrounded 

 by groups or wreaths of forcipate or minor pedicellarise, but similar 

 pedicellariae may be scattered between the dorsal spines, or among 

 the papulae, or they may form dermal clusters. 



*The genus Stellonia, as understood by L. Agassiz (Prod., p. 191, 1835), 

 included not only the present genus Asterias (sens, ext.), but also Echinaster, 

 Solaster, Heliaster, etc. The first species cited was S. rubens (L.). 



