REPORT ON THE ASTEROIDEA. 73 
Incipient pedicellariz, formed of two or usually three modified papille, are present on 
some of the plates, 
The anal aperture is subcentral, but very indistinct. 
The madreporiform body is of enormous size and of compound structure, being 
apparently made up of a number of plates. It occupies a subcircular area extending from 
the marginal plates to nearly midway between the margin and the centre of the disk, its 
diameter being about 11mm. The surface of this area is covered with paxille, which 
are larger and more widely spaced than the paxillz of the abactinal surface generally, and 
have their spinelets radiating nearly horizontally. The striation furrows are thus hidden 
from superficial view, but may readily be seen when the spinelets are removed. The strise 
are of simple construction, and may easily be abraded. Amongst the paxille upon the 
madreporite are a considerable number of simple pedicellarize, formed of three or four 
thickened spinelets. In addition to its great size the madreporiform body is rendered 
more conspicuous by being abruptly raised above the general level of the abactinal surface, 
which causes it to have a button-like or ‘‘ put on” appearance. 
The ambulacral tube-feet have a small flatly conical termination. 
Colour in alcohol, a bleached yellowish white; with sometimes darker shades of dirty 
grey, or even patches of light brown upon the disk. 
Localities.—Station 44. Off the coast of North America, east of Maryland. May 2, 
1873. Lat. 37° 25’ 0” N., long. 71° 40’ 0” W. Depth 1700 fathoms. Blue mud. 
Bottom temperature 36°°2 Fahr. ; surface temperature 56°°5 Fahr. 
Station 45. Off the coast of North America, east of Delaware. May 3, 1873. Lat. 
38° 34’ 0” N., long. 72° 100” W. Depth 1240 fathoms. Blue mud. Bottom tempera- 
ture 87°°2 Fahr. ; surface temperature 49°°5 Fahr. 
Remarks.—This species is distinguished from all the others by its rigid rectangular 
rays, by the enormous and conspicuous madreporiform body, by the small and very com- 
pact paxille of the abactinal surface; and by the small and indefinite spinelets on the 
actinal surface of the adambulacral plates. The characters which separate it from Dytaster 
nobilis are discussed in the comparative description of that form. 
4, Dytaster nobilis, n. sp. (Pl. IIL figs. 1 and 2; Pl. XXXII. figs. 3 and 4). 
This form is nearly allied to Dytaster madreporifer, with which I at first ranked it as 
a variety. On closer study I consider it to be a distinct species. It differs from Dytaster 
madreporifer in its larger size, greater development of disk, and shorter rays, the respec- 
tive dimensions being R= 132 mm.; r=29 mm.; R= 4:5 r. The rays are broader and 
more depressed, though with a more definite median carination. The paxille are larger, 
more distinct, and with fewer spinelets, which radiate from the small tabulum, the centre 
of which is often void, and often provided with a central granuliform spinelet. The 
crown of the paxilla has the appearance of being sheathed in a continuous membrane, con- 
(ZOOL. CHALL. EXP.—PART LI.—1887.) 10 
