162 BULLETIN 100, UNITED STATES NATIONAL MUSEUM, 



the difference. (PI. 40, fig. 3c'.) Besides the pedicellariae the plates 

 bear upward of 10 slender spinelets. 



Adambulacral armature : Furrow spines 6 or 7, long, fairly slender, 

 terete, and sharp, and when dry minutely thorny. They show no 

 sign o:^ the compression characteristic of evaulus, and they usually 

 extend in a fanlike series horizontally across the furrow, being nearly 

 equal, except that either or both laterals may be shorter and slenderer, 

 especially when there are 7 spines to the series. Subambulacral 

 spines usually in 2 series. In the first are 5 to 8, of which 1 near the 

 center is enlarged and nearly or quite as large as the median furrow 

 spines ; the rest are either successively shorter as at the base of ray 

 or abruptly shorter. The outer series consists of 5 to 8 spinelets 

 similar to those of the actinal intermediate plates. Along either 

 transverse margin of plate are 2 or 3 spinelets belonging to the 

 above series, with sometimes 1 or 2 added. On the outer half or 

 third of the ray the enlarged subambulacral spine is considerably 

 longer and stouter than the furrow spines, for the reason that it 

 remains nearly uniform in size while the furrow spines rapidly 

 shorten. Subambulacral pedicellariae are so rare as to be a negligible 

 character. The first adambulacral plate is not compressed, though 

 a little wider than the succeeding. 



Mouth plates broad and convex, a trifle broader in proportion to 

 length than in evmdus. Marginal spines 6 to 8, terete, tapering, 

 pointed, the inner about half as long as the plate, the rest successively 

 shorter. Suboral spines numerous and smaller, in a well-defined 

 series of 8 to 10 along the edge of the median suture, decreasing in 

 length from the teeth outward, and in about 2 irregular inter- 

 mediate series. The marginal series, as in evaulus^ is continued by 

 smaller spines along the adambulacral margin. 



Madreporic body large, less than its own diameter from margin, 

 and with about 12 paxillae on the surface. One of them is very much 

 larger than the rest, this difference not being evident in the type of 

 evaulus^ though indicated in a less extreme form in the small specimen 

 from station 3601. 



Anatomical notes. — Stomach large, and not divided into dorsal and 

 ventral divisions; hepatic coeca short, extending only about one- 

 fifth the length of ray ; intestinal coecum small and in the form of a 

 simple ovoid sac; anal aperture small. Gonads not confined to inter- 

 radius, but in the form of a series of several independent tufts, 

 diminishing rapidly in size distad and reaching nearly to the middle 

 of ray. Polian vesicle in each interradius except that of stone canal ; 

 ampullae large, 2-parted. Superambulacral plates very small, want- 

 ing opposite the first, and either very rudimentary or absent opposite 

 the second ambulacral plates. 



Type.— C^t. No. 37013, U.S.N.M. 



