140 BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



Mouth plates of the same shape as in variabilis, with eleven or twelve to sixteen 

 furrow spinules, the innermost two being abruptly enlarged to form teeth; the 

 othei-s form an independent con;ib and are subequal or the mesial a trifle the longest. 

 Five to seven spines stand on the surface of the i)late, four or five parallel with 

 tlie suture margin and the rest between them and the free margin, forming thus 

 a triangular group. 



Type.— Cat. No. 27S01, U.S.N.M. 



Type-locality. — Albatross station 3337, south of Unimak Island, Alaska, 2S0 

 fathoms, green nuid, rocks. 



Distribution. — Known only from type-locahty. 



Specimens examined. — Four from the type-locality and two without labels." 



Remarl-s. — Typical examples of this species have the secondary or accessory 

 ahactinal spinules about intermediate in ])oint of development between aciculosus 

 and vanabilis. The species diffei-s from aciculosus in the presence of numerous 

 pedicellariic, more numerous furrow spines, and stouter spines generally, as well 

 as larger disk. The madreporic body is situated more than its own diameter from 

 the margin in pedicellaris; less than its diameter in aciculosus. The more extensive 

 and constant papular areas, the numerous ahactinal pedicellariie, and slightly 

 more numerous furrow spines will serve to distinguish pedicellaris from variabilis. 

 In pedicellaris there are twenty adambulacral plates to the first ten superomarginals 

 (not counting the odd interradial) ; in variabilis there are twenty-two; in aciculosus, 

 nineteen or twenty. 



Genus MYONOTUS Fisher. 



Arantharchaster Fisher (part), Zool. Anz.. vol. 35, March 29, 1910, p. 551. 



Myonotus Fisher, Ann. and Mag. Nat. Hist., ser. 8, vol. 7, Jan., 1911, p. 91. Type, Acanthar- 

 chaster intermedius Fisher. 



Diagnosis. — Benthopectinida! similar to Nearchaster but difl'ering in having the 

 papulae confined to the disk and proximal seventh of ray; in the comparatively 

 few marginal mouth sj)ines, regularly graduated in length toward the inner teeth, 

 and in the very stout dorsal muscle bands; marginal plates very spin}^ (two or 

 three superoniarginal and at least three inferomarginal spines) ; primary ahactinal 

 ])lates of i)apular areas strongly lobed and in the form of tabulate paxilla:-, bearing 

 a large central spine, and a circle of small spinelets on the tabulum; odd interradial 

 marginals present in all interradii, tlu^ unpaired superomarginal not conspicuously 

 larger than neighboring plates, and its spines not larger than succeeding supero- 

 marginal spines; atlainbulacral furrow spines one to three, long; subambulacral 

 spines, two. 



Remarks. — This genus resembles Nearchaster in the following points: very 

 spiny marginals; general structure of the lobed, tabulate, spiny, primary ahactinal 

 plates; the rather inconspicuous odd interradial marginals, these not being promi- 

 nent as in Benthopecten, nor having more conspicuous spines than the other supero- 

 marginals. It differs from NearcliaMer in having the papulje confiined to the <lisk 

 and proximal seventh of ray, in having much stouter dorsal muscle bands, and 

 moutli i)lates with few marginal spines regularly graduated in length toward the 

 inner teeth. 



a Bottle broken by earthquake, 1906. 



