248 BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



b-. Abactinal plates forming a composite reticulated meshwork, inclosing large papular areas; adam- 

 bulacral armature: furrows serieB consisting of one spine with fleshy knob , and one smaller actinal 

 epine, the latter hidden in a continuous membranous fold parallel to furrow; marginal plates 

 obliquely placed, strongly imbricating, more or less pear-shaped; no localized pedicellarise, 



but soinolinif'sgranuliform pedicellarise on papular areas Dcrmasterias Perrier, p. 248. 



n^. Marginal plates with spines or epinelets. 

 i' . Abactinal plates rounded, forming fairly regular longitudinal series; numerous actinal intermediate 

 plates; all plates covered and mostly obscured by thick skin; a medioradial and superomarginal 

 series of spines; superomarginal plates forming the margin and bearing large isolated spines; 

 abactinal plates in a definite medioradial and parallel series; abactinal plates forming also 

 regular transverse series, the medioradial elongated longitudinally, the dorsolaterals elongated 



transversely (not rounded as stated by Sladen) Astcrope" Muller and Troschel. 



6'. Abactinal plates not forming regular longitudinal series; no very prominent median radial series 

 as in AstcTopc. 

 c'. Abactinal area devoid of plating; actinal intermediate plates forming isolated bands in trans- 

 verse series Tylaster Danielssen and Koran. 



c'. Abactinal area plated; actinal area with large intermediate plates. 

 (/'. Plates covered with thick skin, usually devoid of spines, or only rare isolated ones present. 



Porania Gray. 



d'. Plates usually spinous, or with the whole membrane closely crowded with miliary spinelets. 



e'. Inferomarginal plates with a flattened comb of spinelets which form a broad marginal 



fringe Murginaskr Perrier. 



e^. Spines when borne on the marginal plates grouped and inconspicuous, not forming a mar- 

 ginal fringe; papulae isolated or grouped Poraniomorphab Danielsson and Keren. 



Genus DERMASTERIAS Perrier. 



Dcrmasterias Pehrier, R6\-ision des Stell^rides, 1875, p. 282. Type, Dcrmasterias incrmis Per- 



rier=.'ls(€ro;wi'.s imhricata Grube. 

 Asteropsis of Authors, previous to 1875, and A. Agassiz, North American Starfishes, 1877, p. 106 



(not Asteropsis Muller and Troschel). 



Diagnosis. — Stellate, mth moderately large, obliquely placed, imbricating 

 marginal plates ; whole test covered with a thick leathery skui obscuring the plates ; 

 no spines except on adambulacral plates; abactinal plates forming a meshwork 

 inclosing large papular areas; papulte numerous; adambulacral plates with a single 

 furrow spine, and one actinal, the former webbed in a continuous series along 

 furrow, the latter immersed in a continuous parallel fold of thick skin ; granuliform 

 abactinal, and valvate adambulacral, pedicellarise sometimes present. 



Only one species known. 



o Within the year 1840 Asterias carini/era Lamarck was made the type of three genera: Astarope 

 Muller and Troschel, Asteropds Muller and Troschel, and Gymnasteria Gray. The first was described 

 in April (Monatsb. preuss. Akad. Wiss. Berlin, p. 104), the second in September (Archiv f. Naturgesch., 

 p. 322), and the last in December (Ann. and Mag. Nat. Hist., vol. 6, p. 278). Muller and Troschel 

 thought that their Astcrope was invalidated by Aslcrope Philippi (for a crustacean), published in June 

 of the same year in Archiv f. Naturg., Heft 2, p. 186, so that they changed the name to Asteropsis in 

 their article Ueber die Gattungen der Asterien, published about September in the same journal, p. 322. 

 Investigation proves, however, that PhiUppi's name was published fully two months after that of 

 Muller and Troschel, the e\'idence being a reprint of Philippi's article in the Annals and Magazine 

 of Natural History, vol. 6, September, 1840, p. 89. This translation states that it is reprinted from 

 Wiegmann'a Archiv, Heft 2, June, 1840, thus fixing the date. There is no reason why Astcrope should 

 not replace Gymnasteria. Sladen was in error. 



ft Includes Rhegaster Sladen and Lasiaster Sladen. See Grieg, Bei^ens Museums Aarbog, 1906, 

 No. 13. p. 41. 



