MUSEUM OF COMPARATIVE ZOOLOGY. 21 
small, prominent, rounded, soft verruce, having the outer surface composed of 
a layer of special nettling cells; these verruce also extend over the basal part 
of the lower calicles. They may, perhaps, be of the same nature as the zodids 
of Pennatulacea. 
Iridogorgia Pourtalesii VERRILt, sp. nov. 
Plate Il. Figs. 7, 7a 
Main stem strong, rather rigid, calcareous, growing in a remarkably regular, 
open, upright spiral or helix. Base not obtained. Branches numerous, long, 
slender, delicately tapered, flexible, undivided; they arise very regularly, at 
intervals of about 4 to 6 mm., in a single row, along the side of the main 
stem that forms the outside of the spiral, and spread out laterally and widely, 
nearly at right angles to the stem, so that the whole coral has a broad spiral 
form, something like the skeleton of a spiral staircase. 
The axis, in our example, makes about five volutions; its apex becomes 
slender and acute, but the lower end is incomplete. 
The cenenchyma is thin, and filled with slender fusiform spicula beneath the 
surface, which is soft, and bears numerous minute, rounded, elevated, soft ver- 
ruc, which cover the main stem and proximal part of the branches, extending 
also over the basal portion of their proximal calicles, but they gradually be- 
come smaller and disappear farther out on the branches. 
Calicles are not found on the main stem, except rarely one close to the origin 
of a branch; on the branches they are placed singly, and rather far apart, along 
the upper side; the distance between them is usually from 5 to 10mm. The 
ealicles are mostly broader than the branches on which they are situated; they 
have a swollen basal part, extending somewhat along the branch; the upper 
part is verruciform, and is usually surmounted by the large, incurved tentacles, 
which do not appear to be capable of entire retraction. The proximal calicles 
(Fig. 7) are the largest, and have very large tentacles, with swollen translu- 
cent stems, in which there are only a few slender spicula, close to the base; the 
pinne are elongated, slender, and without spicula. The calicles are filled with 
slender, nearly smooth, acute spicula, oblique and transverse in the basal por- 
tion, but becoming longitudial at the summit, between the bases of the tentacles. 
In alcohol, the color of the calicles, tentacles, and coenenchyma is white; the 
denuded axis and branches have a bright golden or pale bronze-like lustre, 
and reflect brilliant iridescent colors, in which light green and golden yellow 
predominate; by transmitted light the axis of the branches is pale wax-yellow 
and light amber. 
Height of main stem, 200 mm.; diameter at lower end, about 2 mm.; diam- 
eter of larger branches, at base, 1 mm. or less. The larger, upright, fusiform 
spicula in the distal part of the calicles measure .56 by .04, .48 by .04, 
46 by .05, .42 by .04 mm.; those of the basal part of the calicles, .55 by .05, 
55 by .04, .52 by .05, .50 by .04, .42 by .035, .42 by .025, .28 by .03, 
