406 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



The features which seem to ally Metrodira to the Echinasteridae 

 are: The single ampullae, spinose abactinal plates, and the adambu- 

 lacral armature. The intermarginal plates and the very reduced ac- 

 tinal intermediate areas are quite consistent with this family, but 

 the very conspicuous marginal plates are not. The interbrachial 

 septa are very rudimentary, practically absent, although it is not 

 possible in the small specimens at my disposal to be certain of this 

 point. 



Beyond a certain similarity due to the outward form, particularly 

 to the slender rays, the Linckiidae have little claim to this genus. 



The presence of intermarginal plates and of single ampullae, and 

 the absence of actinal intermediate plates and of interbrachial septa 

 with calcified pillar will debar Metrodira from the Asteropidae, 

 Ganeriidae, and Poraniidae, while additional differences in the abac- 

 tinal skeleton make the last two families unsuitable homes. 



Even the Echinasteridae appear to be incompatible. The abactinal 

 plates of Metrodira are tessellated, not at all reticulate, while the 

 marginal plates are large, compact, and form a vertical side to the 

 ray. The interbrachial septa are almost lacking. 



It seems better to place this genus in a separate family rather than 

 to enlarge the Echinasteridae and in a measure spoil its homogeneity. 

 The case of Metrodira is much like that of Acanthaster, Mithrodia, 

 and Valvaster. which have at one time or another been in the Echi- 

 nasteridae. 



METRODIRA SUBULATA Gray. 



Metrodira subulata Gray, 1840, p. 282. — Perriek, 1875, p. 180. — Koehleb, 

 1910a, p. 172, pi. 4, figs. 1 and 2; pi. 18, fig. 9; 1910b, p. 284, pi. 15, 

 fig. 3 ; pi. 17, fig. 3, 4, 5. 

 Scaphaster humberti de Lobiol, 1899, p. 27, pi. 3, fig. 1. 

 Doctor Koehler^ has given a detailed description and figures 

 of this species. The Philippine examples, the larger measuring 

 R, 25 mm., and r, 4 mm., are less spiny abactinally. The proximal 

 plates of the intermarginal series are nearly as large as the adjacent 

 inferomarginals, and there is usually an odd interradial intermargi- 

 nal plate, but not an odd supero- or inferomarginal. The intermar- 

 ginals extend about half the length of ray. 



Type-locality. — Migupou (probably a Philippine locality). 

 Distribution. — Macclesfield Bank; Philippine Islands; Torres 

 Strait ; Aru ; Amboina ; northwest of Australia ; northeast Australia ; 

 George Sound, New Zealand ; Bay of Bengal ; Ceylon. 

 Specimens examined. — Two from the following stations : 

 Station 5431, off Corandagos Island, eastern Palawan, 51 fathoms, 

 sand. 

 Station 5432, same locality, depth, and bottom. 



lAbhandl. Senckenberg. Naturf. Gescel., vol. 33, 1910, p. 284. 



