ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER. 169 



Leptogonaster and Axtheniaster. — About the only difTerence between Lcp- 

 togonaster Sladen and AntheniasterYerr'iW is the wider distribution in tlie latter of sec- 

 ondary abactinal plates. AntTieniaster epixantJius Fisher varies considerably, how- 

 ever, in the number of abactinal secondary plates. Young specimens have no more 

 than the adradial row, described by Sladen (1889, p. 330), in the type of Leptogon- 

 aster cnspatus. The character of the abactinal plating, the granulation, actinal 

 interradial areas, and especially the adambulacral armature and abactinal membrane 

 are essentially alike in botii species, or not different enough to warrant two genera. 

 Anthenoides is the nearest relative. Its differences are brought out in the key. As 

 Professor Verrill classed ni}- ep'ixantlms in Antheniaster, I have felt justified in using 

 that species for comparison. I now think it is a Leptogonaster, intermediate in 

 respect to the abactinal plating between crispatus and sarissa (.Vlcock) and differing 

 specifically in details of abactinal and marginal granulation, in the adambulacral 

 armature, and distribution of pedicellariae. 



Ogmaster. — It is rather curious that this genus should have been classed next 

 to " Goniodiscus," as its appearance is so unlike any species of that group. In the 

 specimen in the Museum of Comparative Zoology (467) the abactinal membrane 

 must be very thin, for it is scarcely apparent in the dried specimen. There are no 

 secondary abactinal plates, and only the plates of the papular areas have slight 

 lobes. There are no granules on any plates but the adambulacrals and mouth 

 plates. This agrees with Gray's figure" and description* of " Dorigona lieevesii," 

 which is the same as Ogmaster capeUa. Sladen's comparison of the genus with 

 SteTlaster in his key (1889, p. 264), stating that the test is overlaid by a granulous 

 membrane, is not only misleading, but is contradicted in the very next line. There 

 is no particular similarity between SteUaster and Ogmaster. 



KEY TO THE KNOWN GENERA OF OONIASTERID.E. 



I. Abactinal platps tabulate on the radial areas and often paxilliform, never flat nor covered with a 

 continuous membrane, 

 a'. Superomarginal plates not contiguous on the rays, one or more series of abactinal plates reacliing 

 the terminal plate (occasionally a few distal plates in contact). 

 6'. Abactinal plates stellate with paxilla;; actinal intermediate areas with imbricating plates in 



transverse series bearing paxilliform groups of spines Mimasler Sladen. 



6-. Abactinal plates with tabuhite paxilliform platt's; actinal intermediate areaa with imbricating 

 plates bearing coordinate granules or spineleta. 

 c'. An unpaired (but not recurved) median tooth common to each pair of mouth plates; pedi- 

 cellariie when present fasciolar, rarely valvular; superambulacral plates present, though 

 frequently very small. 

 d '. Adambulacral armature: furrow series radiating, subpalmate; actinal spines in a coordinate 

 group, frequently one slightly enlarged, appressed; inferomarginals usually with a few 

 appressed enlarged spinelets. 

 «'. Several series of abactinal plates extending far along ray and usually more than one 

 attaining the terminal plate; rays fairly broad; superambulacral plates fairly well 

 developed; pedicellariae pectinate, fasciolar, or valvular. .Pscudarchasttr Sladen, p. 179. 

 e'. Superomarginal plates of ray separated by single series of roundish or quadrate granulated 

 (not paxilliform) plates; superambulacral plates rudimentarj'.": Xo pedicellarioE. 



raragonastcr Sladen. 

 d '. Furrow series of spines not radiating or subpalmate. 



" Synopsis, pi. 7, fig. 3, 3a. 



* Idem, p. 7. 



« Superambulacral plates rudimentary in raragonastt r formosus (Verrill'). 



