204 BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



roundish, the median radial witli one central and six to nine peripheral terete blunt 

 spinelets. There are four lono; furrow spinelets and one of the two or three actinal 

 adambulacral spinelets is longer than the rest. The marf:;inal plates are more 

 conspicuous in the adult. 



Type.— C&t. No. 22337, U.S.N.M. 



Type-locality. — Albatross station 4427, o(T Santa Cruz Island, Cahfornia, 447 

 to 510 fathoms, black mud, rocks. A young specimen from station 4421, between 

 Santa Barbara and San Nicholas Islands, 291 to 229 fathoms, gray mud, rocks. 



Disiribution. — Southern California south probably intergrading with M.transfuga 

 Ludwig of the Panama fauna (the two species may be the same). Found in 291 to 

 510 fathoms. 



Bemarlcs. — The species most closely related to the present is Mediaster transfuga 

 Ludwig (1905) from the ^^cinity of Acapulco, 902 meters. It is probable that the 

 two forms are merely extremes of the same species, as the outward habit and most 

 of the structural details are essentially the same. M. transfuga has slightly longer 

 rays and longer lobes to the dorsal plates; the area of the internal connecting 

 ossicles is somewhat more restricted (possibly due to younger specimens) ; there are 

 fewer spinelets to the dorsal paxillse; adambulacral sjiiuelets are shorter (?), especi- 

 ally on the actinal surface of plate; the actinal pedicellariiB when present are like 

 the doi-sal; in teneUus they are much higher, almost spiniform. Probably rudi- 

 mentary superambulacral plates are present in transfuga and escaped notice. It is 

 impossible to tell how much the characters of tyjjical teneUus vary, as only one adult 

 was taken by the Albatross. 



The Mediaster elegans described by Ludwig in the same paper (1905, p. 125) 

 is not a Mediaster, as it lacks the distinctive characters of the genus. 



Mediaster teneUus is remarkable for the small marginal plates, the high, slender, 

 pedicellarise of the actinal surface, and for the imusually long furrow spinelets. 

 The peripheral spinelets of the abactinal paxiUje are also more elongate than is 

 usual in the genus. The species is therefore far removed from sequalis, the type 

 of the genus. 



Genus CERAMASTER (Verrill). 



Ceramaster Verrill (Sec. C of Tosia), Trans. Conn. Acad., vol. 10, 1899, p. 161. Type, Asterias 

 granularis Retzius. — Fisher, Bull. U. S. Fish Comm. for 1903, pt. 3, 1906, p. 1054 (subgenus). 



Pentagonasler Authors (not Gray) in part. 



Tosia Verrill (not Gray) in part, 1899. — Fishek, 1905. 



Mediaster Verrill in part, 1899. 



Philonaster (subgenus) K<ehler, Deep Sea Asteroidea collected by the Roy. Ind. Mar. Surv. 

 Ship Investigator, 1909, p. 74. Type, Pentagonaster (Philonaster) mortenseni Kcehler. 



Diagnosis. — Goniasteridie with a pentagonal, arcuate pentagonal or very shorts 

 rayed form; with the abactinal plates entirely covered with granules, those of 

 papular areas with more or less elevated (sometimes almost paxiUiform) tabula, 

 the base being slightly to conspicuously lobed; marginal plates granulated, some- 

 times with a plane or tumid naked area; actinal intermediate plates always gran- 

 ulated; adambulacral plates with two to eight fiuTow spinelets, their actinal gran- 

 ules frequently in series, graduated in size between furrow spinelets and actinal 



