WEST INDIAN STARFISHES 35 



1894. Ludwig, Fauna Arctica, i, p. 472, 1900. Fisher, op. cit., 19116, 

 p. 258, analytical table known genera, p. 259. Verrill, op. cit., p. 205, 

 1814a. 



Dorsal skeleton usually formed of small, sometimes over- 

 lapping, reticulated or areolated plates; sometimes they form 

 longitudinal radial rows. Median dorsal row is often indistinct. 

 Upper marginals small, often not specialized. Inferomarginals 

 usually distinct. One or more interactinal rows are usually 

 present. Dorsal and marginal spines may be large and isolated 

 or minute and clustered, but not truly paxilliform. They are 

 often covered with a distinct, thick, dermal membrane, which 

 may contain calcareous granules. 



The ambulacral ampullae are usually single, one to each tube- 

 foot. 



Ambulacral grooves narrow. Adambulacral spines small, two 

 or several to a plate, usually in a transverse group or a single 

 transverse row. No pedicellarise are known. 



The most prominent genera are Echinaster and Henncia, both 

 of which occur in the West Indies. 



Genus E chest aster Miiller and Troschel, emended. 



Echinaster (pars) Miiller and Troschel, Monatsber., Berlin. Wis. Akad., 

 April, 1840, p. 102; Wieg. Arch., 1840 (non Gray); Syst. Aster., p. 

 22, 1842 (pars). 



Othilia Gray, Ann. Mag. Nat. Hist., vi, p. 281, Dec, 1840; Synopsis Star- 

 fishes, p. 12, 1866. Fisher, 19115, p. 260. 



Echinaster Perrier, Eevis. Stell. du Mus., Arch. Zool. Exper., iv, p. 364, 1875. 

 A. Agassiz, North Amer. Starfishes, p. 97, pi. x, 1877 (structure of 

 skeleton.) Viguier, Squelette Stell., Arch. Zool. Exper., vii, p. 123, pi. 

 vii, figs. 1-7, 1878 (structure of skeleton.) Sladen, Voy. Chall., Zool., 

 XXX, p. 553, 1889. Perrier, Exp. Trav. et Talism,, p. 146, 1894. Ver- 

 rill, op. cit., p. 206, 1914a. 



Stellate, usually with the disk rather small. Rays normally 

 five, of moderate length, rounded. Larger dorsal and marginal 

 plates strong, lobate, convex in the middle, and having a central 

 mammilla and pit for the attachment of the usually solitary 

 spine. The larger ossicles are united into reticulations by small, 

 rounded, connective ossicles, leaving large papular areas; soli- 

 tary papulae may occur in the marginal and actinal regions. 



The whole surface is covered in life with a rather thick, soft 

 integument, containing small granules on the spines. Dorsal 



