138 THE VOYAGE OF H.M.S. CHALLENGER. 
one small conical spinelet at the junction of the pair of plates and two others on the 
margin of each plate. The odontophore is visible. The actinal interradial areas are 
covered with a complete pavement of plates. 
Localities.—Station 45. Off the coast of North America, east of Delaware and 
Maryland, May 3,1873. Lat. 38° 34’ 0” N.,long. 72° 10’ 0” W. Depth 1240 fathoms. 
Blue mud. Bottom temperature 37°°2 Fahr.; surface temperature 49°°5 Fahr. 
Station 46. Off the coast of North America, east of New Jersey. May 6, 1873. 
Lat. 40° 17’ 0” N., long. 66° 48’ 0” W. Depth 1350 fathoms. Blue mud. Bottom 
temperature 37°°2 Fahr.; surface temperature 40°:0 Fahr. 
Station 47. Off the coast of North America, east of New Jersey and Long Island. 
May 7, 1873. Lat. 41°14’ 0” N., long. 65° 45’ 0” W. Depth 1340 fathoms. Blue 
mud. Surface temperature 42°°0 Fahr. N 
Remarks.—This species is at once distinguished from the other members of the genus 
by the single cribriform organ in each interbrachial arc, by the absence of seomental 
pits and papille, by the short rays, and by the spinelets on the abactinal membrane 
being confined to limited areas which occupy the interradial lines and the central region 
of the disk. 
2, Porcellanaster caulifer, Sladen (Pl. XXI. figs. 5-10; Pl. XXVII. figs. 9-12). 
Porcellanaster caulifer, Sladen, 1883, Journ. Linn. Soc. Lond.|(Zool.), vol. xvii. p. 222 
Rays five. R=21 mm.; r=6°5 mm. Ress 
Rays moderately long and slender, not much broader at the base than at mid-arm, 
tapering only slightly, the minor radius in the proportion of 30 per cent. Interbrachial 
ares rather flatly rounded. Disk high and much inflated. 
The. abactinal area is covered with an integument, beset with spinelets, excepting at 
the very base of the rays. The spinelets are simple, delicate, clavate, or thickened at 
the extremity, covered with membrane, and rather widely spaced. Large papulz-like 
bodies are distributed here and there. A very long tubular epiproctal prolongation or 
anal funnel rises from the central region of the disk, in length nearly equal to the 
minor radius, rather narrow and tapering towards the extremity. 
The marginal plates are moderately high, and form a perpendicular wall in the 
interbrachial are, but arch over on the abactinal surface of the rays, and leave only a 
narrow space along the median line between the corresponding plates of the two sides. 
The supero-marginal plates are seven in number, exclusive of the terminal; all are longer 
than high, and each carries a long, delicate, acicular spinelet. The terminal plate is 
large and elongate, very slightly prominent abactinally, and flattened; it normally 
carries three spinelets, though sometimes more are present. These are longer than 
the spinelets on the other supero-marginal plates, and are delicate and acicular; one 
