12 BULLETIN 76, UNITED STATES NATIONAL MUSEUM 



Remarks. — Brisingenes mimica and B. anchista of Buton Strait, Celebes (Fisher, 

 1919, pp. 518, 521), are in most respects closely similar to Brisinga, s. s., except for 

 the regular circle of papulae near the margin of the disk, there being two papulae for 

 each radius. The first pair of adarnbulacral plates is more closely joined than in 

 true Brisinga judging by the figure of B. endacnemos Asbj0rnsen given by G. O. Sars 

 (1875, pi. 7, figs. 8 and 9) and the condition of these plates in B. trachydisca. The 

 outer ends of the plates tend to radiate apart somewhat, and in the latter species the 

 united first pair of marginals slips down between them. 



No member of this genus is known from the north Pacific. 



Genus BRISINGELLA Fisher 



Brisingella Fisher, Ann. and Mag. Nat. Hist., ser. 8, vol. 20, p. 427. Type, Brisinga 

 fragilis Fisher; Bull. U. S. Nat. Mus., 100, vol. 3, 1919, p. 523. 



Diagnosis. — Differing from typical Brisinga in having only one gonad on either 

 side of each ray; in having the first adarnbulacral plate separated from that of the 

 adjacent ray by the outer ends of the combined mouth plates; in having the inter- 

 radial pair of marginal plates joined only by the adoral ends, and forming a A-shaped 

 structure with the unpaired interradial plate. Rays slender, usually very deciduous, 

 a nonmuscular symphysis or syzygy uniting first and second adarnbulacral plates 

 and the dorsal part of the second and third ambulacral plates; adarnbulacral plates 

 longer than broad, with few or no furrow spinelets, and a sharp, unmodified, sub- 

 ambulacral spine; integument of disk thin, weak; mouth plates small, with small 

 suboral spine; entrance of furrow into actinostome broad. 



Remarks. — This genus includes a number of species of the old genus Brisinga 

 which are very distinct from the type, B. endacnemos. They are outwardly dis- 

 tinguished by the delicate rays which are very deciduous, by the delicate dorsal 

 skeleton, both of disk and rays, by the thin disk, and more definitely by the fact that 

 the first adarnbulacral plate is not united with its neighbor of the adjacent ray, but 

 is separated by the outer end of the combined mouth plates. Correlated with this, 

 the first marginal plate is not joined to its ris-a-vis as in typical Brisinga, forming 

 thus a pair of plates snugly apposed, above the closely apposed first adambulacrals. 

 But instead they join only by their adoral or inner ends, and with the interradial 

 plate form an inverted Y-shaped structure, the two arms of which represent the first 

 marginal plates, while the acute angle represents the interbrachial angle bounded by 

 these plates. If the lateral face of a disk which has lost several rays is examined it 

 will be noted that the rays have broken at the syzygial or nonmuscular symphysis 

 between the first and second adarnbulacral plates. In Brisinga one sees two distal 

 facets close together and immediately above them two smaller, usually unequal, 

 closely joined facets— the distal ends of the first marginal plates. The two lower 

 (adarnbulacral) facets are very slightly spaced. In BrisingeUa the adarnbulacral 

 and marginal plate of each ray are joined, the former above the latter, but never 

 those of adjacent rays. Always the interbrachial angle or sinus extends to the 

 proximal end of the plates and keeps those of adjacent rays apart. 



More important still, in Brisinga the gonads are numerous in each ray and 

 form a series of independent bodies along either side of the genital region. In 



