530 BULLETIN 100^ UNITED STATES NATIONAL MUSEUM. 



Articular surface of the ambulacral plates at junction of ray with 

 disk considerably broader than high. Each scar is rather oval in 

 contour, and the lower ends do not diverge very markedly from the 

 median vertical suture. Gonads, first adambulacral plates, and first 

 marginal plates as in generic description. 



Type.— C2it. No. 37023, U.S.N.M. 



Type-locality. — Station 5440, mouth of Lingayan Gulf, Luzon, 172 

 fathoms, fine gray sand, giobigerina, bottom temperature, 53.2° F. ; 

 1 specimen. 



Distribution. — ^Known only from the type-locality. 



Remarks. — This si^ecies resembles A. iiioluccana., but lias only 11 

 rays, a much smaller disk with a beveled border, and 1 to 3 minute 

 spinelets to each plate of the disk, instead of only 1, no abactinal 

 disk pedicellariae, much longer lateral spines, and the minor sub- 

 ambulacral spinule is larger, as well as further from the adoral 

 furrow spinelet. There are 2 suboral spines, relatively larger than 

 in moluccana. 



Genus STEGNOBRISINGA Fisher. 



Stegno'brisinga Fisher (subgenus), 19166, p. 33; 1917f, pp. 423, 428. Type, 

 Brisinga (Stegnobrisinga) placoderma Fisher. 



Diagnosis. — Resembling Brisinga in general appearance, and espe- 

 cially in having definite transverse skeletal ridges, or costae, on the 

 genital region, but differing in having the integument between the 

 costal arches of ray strengthened by many close-set, mostly contigu- 

 ous or sometimes overlapping, papery, spineless plates of irregular 

 form, completely filling the interspaces; in having 2 gonads to each 

 ray. Proximal subambulacral spines acicular; first adambulacral 

 plate and first marginal plate joined for their whole length to the 

 respective plates of adjacent ray; thus there are 4 closely joined 

 plates in each interradius; a nonmuscular symphysis, or syzygj^, 

 uniting first and second adambulacral plates and between the upper 

 parts of the second and third ambulacral plates, as in Brisinga. 



Remarks. — The numerous prominent costae will at once separate 

 this genus from Freyella and FreyeUastc'}\ while the number of gon- 

 ads, 2 to a ray, is an added distinguishing feature so far as Freyel- 

 laster is concerned. The structure of the first adambulacral plates, 

 and the presence of proximal marginal plates will sharply distinguish 

 Stegnobrisinga from FreycUa. 



The genus AsfroU7iis, type Brisinga panamensis Ludwig, differs 

 from Stegnobrisinga in having the first adambulacral plates and first 

 marginal plates arranged as in Brisingella, and in having slenderer 

 adambulacral plates, which proximally are not higher than long. 



