REPORT ON THE ASTEROIDEA. 377 
Chorology of the Genus Cycethra. 
a. Geographical distribution :— 
Atuantic: Three species between the parallels of 45° and 55° 8, 
Cycethra pinguis and Cycethra nitida, off Cape Virgins, near the 
Atlantic entrance to the Strait of Magellan. Cycethra electilis, off 
the Falkland Islands. 
Pactric : One species between the parallels of 45° and 55° 8. 
Cycethra simplex, in the Trinidad Channel, west coast of Patagonia. 
B. Bathymetrical range: 12 to 55 fathoms. 
y. Nature of the Sea-bottom: All the species inhabit a sandy bottom. 
Chorological Synopsis of the Species. 
Ocean. Range in Fathoms. Nature of the Sea-bottom, 
Cycethra electilis . : Atlantic. | 12 Sand and gravel. 
Cycethra nitida . el Atlantic. 5d Sand, 
Cycethra pinguis . j Atlantic. 55 Sand. 
Cycethra simplex. ; Pacific. 30 Sand. 
1. Cycethra electilis, n. sp. (P]. LX. figs. 3 and 4; Pl. LXII. figs. 2 and 3). 
Rays five. R=40mm.; r=16 mm. R=2'5 7. Breadth of a ray between the third 
and fourth infero-marginal plates, 15 mm, 
Rays moderately produced and comparatively flat, broadest at the base, and tapering 
gradually therefrom to the extremity, which is rather broad and obtusely rounded. Disk 
capable of slight inflation, which may be emphasised by a faint depression in the median 
interradial line. Margin moderately thick and vertical. Interbrachial ares more or less 
rounded. Actinal surface plane. 
The abactinal area is covered with small plates which bear small paxilliform groups of 
spines. These are composed of from three to seven short, cylindrical, obtusely-rounded, 
equal spinelets, which are erect and covered with membrane, the latter forming a compact 
fleshy mass within the paxilla in which the spinelets are imbedded. Large and smaller 
paxillz are intermixed, but the difference in size is not conspicuous at first sight, and no 
order of arrangement is discernible ; they are distinctly spaced. Numerous papulz are 
present in the interspaces, sometimes two or three together. 
_The marginal plates are small and confined entirely to the margin, occupying the 
(ZOOL. CHALL. EXP.—PART LI.—1888.) 48 
