104 BULLETIN 7(>, UNITED STATES NATIONAL MUSEUM. 



angle, where there are six larger and heavier teeth. General surface of plates 

 covered with small pa])illiform spinelets similar to those of actinal intermediate 

 plates, and increasing in thickness at inner angle. 



Actinal intermediate areas small, the intermediate plates, which are slightly 

 convex, exteniiing to sixth or seventh inferomarginal, those adjacent to the 

 adambulacral plates being largest. The plates are armed with spaced, radiating, 

 small, papilliform spinelets. In a smaller sjiecimen than the type several plates of 

 each area bear a j)eculiar pedicellarian apparatus consisting of three or four shorter, 

 thickened, davate spinelets. These jaws are curved toward each other, and the 

 tip is usually broadened and scoop-shaped. The type has only one or two to 

 each area. 



Madreporic body large, 8 mm. in diameter, situated a little more than half its 

 own diameter distant from the margin, and hidden by about forty lai^e ornate 

 paxillie, which stand flush with the general surface. These paxillae are larger than 

 any on the general abactinal surface and their spinelets are heavier and more 

 clavate, those situated on the peripherj' being slenderer, however, and apparently 

 sharp or even mucronate. 



Anatomical notes. — Superambulacral ossicles present, though very small; 

 absent from first ambulacral, and beyond middle of ray, or else rudimentary. 

 Gonads in very numerous small tufts, these distributed in a Imear series parallel to 

 marginal plates, and extending beyond middle of ray (for about two-tliirds length 

 in type). Upper and lower ends of ambulacral ossicles verj^ broad, the lower 

 end with a median keel. Tube feet large conical pointed, without deposits. Anus 

 present. 



Tj/pc— Cat. No. 22331, U.S.N.M. 



Type-locality. — Albatross station 4397, oif San Diego, California, 2,196 to 

 2,228 fathoms, gray mud; two specimens (all that have been examined). 



Remarks. — Among the species dredged by the ChaUengcr, D. gilherti appears 

 to be nearest D. exilis, but differs from that form in having shorter and broader 

 rays, the sides of which are high, and arched inward toward the dorsal surface 

 distally, in having less crowded i)axillae with a greater number of spinelets, more 

 numerous marginal plates, the ventral series of which do not encroach upon the 

 actinal area to any great extent; a rather less numerous series of furrow spinelets; 

 in ha\nng abactinal j)edicellariic. There is no carination of the rays as in D. exilis 

 carinata. The inward arching of the sides of ray mentioned above is not so pro- 

 nounced in a smaller mutilated specimen from the same station. The shape of 

 the ray is, however, characteristic. The sides are straight or a trifle swollen above 

 the base and do not have the arcuate taper of grandis { = madre porifer Sladen, 

 1889, pi. 3). The paxillar area is broader at base and narrower at extremity than 

 in spinosus, and therefore much wider than in exilis. 



Allowing for variation D. demonstrans Ludwig " appears to be very close to 

 the present species. The marginal plates and proportions are practically the 

 same, but the paxillar area does not appear to narrow so abruptly distad, nor to 



a Mem. Mus. Comp. Zool., vol. 32, 1905 (July 17), p. 41, pi. 5, figs. 23-25; pi. 18, &^s. 97-99; pi. 19, 

 fig. 107; pi. 20, figs. 108-115. 



