STAEPISHjSS of the PHILIPPINE SEAS. 523 



form of the pedicellariae, and by the more numerous prominent 

 costae. The other differences have been fully detailed in the diag- 

 nosis and description. (See also the key.) 



Genus BRISINGELLA Fisher. 



Brisingella Fisher, 1917/", pp. 423, 427, figs. 5 and 6. Type, Brisinga fragilis 

 Fisher. 



Diagnosis. — Differing from typical B^nsinga in having only one 

 gonad on either side of each ray; in having the first adambulacral 

 plate separated from that of the adjacent ray by the outer ends of the 

 combined mouth plates; in having the interradial pair of marginal 

 plates joined only by the adoral ends, and forming a Y-shaped struc- 

 ture with the unpaired interradial plate. Rays slender, usually very 

 deciduous, a nonmuscular symphysis or syzygy uniting the first and 

 second adambulacral plates, and the dorsal part of the second and 

 third ambulacral plates ; adambulacral plates longer than broad, with 

 few or no furrow spinelets, and a sharp, unmodified, subambulacral 

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

 suboral spine ; entrance of furrow from actinostome broad. 



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

 Brisinga which are very distinct from the type, B. endecacne'mos. 

 They are outwardly distinguishable by the delicate rays which are 

 very deciduous, by the delicate dorsal skeleton, both of disk and of 

 rays, by the thin disk, and more definitely by the fact that the first 

 adambulacral plate is not united with its neighbor of the adjacent 

 I'ay, but is separated by the outer end of the combined mouth plates. 

 Correlated with this the first marginal plate is not joined to its 

 vis-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 a Y-shaped structure, the two arms of which represent 

 the first marginal plates, while the acute angle represents the inter- 

 brachial 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 adambulacral plates. In Brisinga one sees 2 distal 

 facets close together and immediately above them 2 smaller, usually 

 unequal, closely joined facets — the distal ends of the first marginal 

 plates. The 2 lower (adambulacral) facets are slightly spaced. In 

 Brisingella the adambulacral and marginal plate of each ray are 

 joined, the latter above the former, 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 



