ECHINODERMS OF SMITHSONIAK'-HARTFORD EXPEDITION CLARK 445 



The first adambiilacral plate bears a long spine, about half again 

 as long as itself, in the median line (as viewed actinally) about 

 one-third of the distance from the proximal to the distal end. Near 

 the distal inner angle of the plate adjoining the ambuJacral groove 

 is a furrow spine about two-thirds the length of the plate. Between 

 this and the large central spine, forming all together a diagonal 

 row of 4 spines, are 2 other spines of which that nearest the furrow 

 spine is a little smaller than the latter, and that near the median 

 spine is larger, about half as large as the median spine. 



The second adambulacral plate has a similar diagonal i*ow of 4 

 spines, but thq large median spine is situated slightly more distally, 

 at or slightly beyond the middle of the ossicle. 



The third adambulacral plate has a diagonal row of 5 spines of 

 which the 3 inner are subequal, small, and slender, the next is larger 

 and stouter, and the outermost, in the center of the plate, is half 

 again as long and much stouter. 



The fourth and fifth adambulacral plates have each a similar row 

 of 5 spines. 



On the seventh adambulacral another spine appears, a long spine 

 half again as long as the plate situated on the outer side just at the 

 edge of the plated abactinal covering of the arm base, and just beyond 

 the large central spine. This spine is absent from the eighth adam- 

 bulacral but occurs on the ninth and twelfth and distally on alternate 

 adambulacrals. 



On the outer adambulacrals the long central spine becomes sepa- 

 rated from the others ; the latter also become smaller, forming a diag- 

 onal line of 4 small sharp spines at the distal angle of the plate. 



On the distal portion of the arm the furrow spines become reduced 

 to three, then to two, and finally to one. 



All the spines are enclosed in skin sacks, which bear numerous 

 minute pedicellariae. 



The adambulacral plates are widely spaced. 



The marginals are very small, less than half as long as the adambu- 

 lacrals. They adjoin the distal outer angle of an adambulacral and 

 run distally along the edge of the ambulacral, overlapping the base of 

 the adambulacral following for about one-third of its length. They 

 are thus widely separated from each other. 



There are no papulae on the disk or on the arms. 



Type.— Fvom Albatross station 2379, Gulf of Mexico (U.S.N.M. 

 no. E.5602). 



/?emary5?s.— Heretofore the family Brisingidae was known to be 

 represented in the Caribbean region only by Hymeiiodiscus agassim 

 E. Perrier, from off St. Croix and Dominica in 391-450 fathoms, and 

 Odinia antilUnsis A. H. Clark, from off Puerto Kico in 280-340 fath- 



