A440 THE VOYAGE OF H.M.S. CHALLENGER. 
Supero-marginal plates large. Infero-marginal plates small, each with one small, 
compressed, horizontally disposed lateral spine, forming a regular longitudinal series at the 
ambital margin. Papulee single, isolated, forming regular longitudinal lines between 
the plates. 
Adambulacral plates small, contingent on the infero-marginal plates, not separated 
by papule. Adambulacral armature consisting of two equal spines which form two 
regular longitudinal rows. 
Adambulacral tube-feet quadriserial in arrangement, with a fleshy, button-like, 
centrally invaginated terminal disk. 
Madreporiform body small, occupying the median area of a basal plate near the 
margin. 
Anal aperture present, excentric, external to the dorso-central plate. 
Chorology of the Genus Tarsaster. 
a, Geographical distribution :— 
Pactric: One species between the parallels of 10° N. and 10° S$. 
Tarsaster stoichodes, off D’Entrecasteaux Reef, North of Ad- 
miralty Islands. 
8. Bathymetrical range: 150 fathoms. 
y. Nature of the Sea-bottom: Coral mud. 
Chorological Synopsis of the Species. 
Ocean. | Range in Fathoms. Nature of the Sea-bottom. 
Tarsaster stoichodes . ; Pacific. | 150 Coral mud. 
1. Tarsaster stoichodes, n. sp. (Pl. CIV. figs. 5-8). 
Rays five R=53mm.; r=5mm. R>107. Breadth of ray at the base, 6°75 mm. 
Rays elongate, rather broad at the base in relation to the small disk, subeylindrical, 
convex, and arched abactinally, tapering from the base to the extremity, slightly con- 
stricted at the base. Disk very small, slightly convex, not higher than the base of the 
rays, the junction of the rays and disk being defined by a depression. 
The abactinal area is beset with relatively large plates. The disk is covered with the 
primary apical plates, very few others being present. The plates upon the rays are 
