Young Stages of Umbellularia. 315 
another terminal polype, which is effected by the first polype 
(hitherto at the top) being removed a little towards one side ; 
and we now get an arrangement (fig. 4) in which there is a 
polype close to the top on each side of the end of the rachis, 
or they both grow out at right angles from the latter; and 
the polypary now, as in fig. 2, presents a perfectly symmetrical 
praia ae viz. two polypes on one side and two on the 
other, 
The end of the rachis is clearly visible in fig. 1, which has 
been drawn from a specimen made transparent; and it is in- 
dicated by a knob in fig. 2. Spicula were not visible in fig. 1. 
Zootds are first to be seen on the ventral side of fig. 2, and so 
they are in fig.3; in the largest of the specimens here figured 
they cover the ventral side of fig. 4 a, but leave free a middle 
line on the dorsal end of the same. 
The mode of growth of the polypes in this Antarctic 
Umbellularia is therefore, so far as our specimens show, as 
follows :— 
1. The terminal polype comes out (fig. 1). 
2. The terminal polype grows, and two lateral ones come 
out (figs. 1 and 3). 
3. The terminal polype loses its place by another one coming 
out, and is removed towards the side (figs. 2 and 4). There 
are now on each side a terminal and a lateral polype (according 
to Lindahl’s nomenclature). 
4, A fifth polype is coming out in the centre of the poly- 
pary (fig. 24, rr.); and the rest of the polypes very likely 
come out below the first two lateral ones. 
In the earliest stage there are neither spicula nor zooids ; the 
latter, when they have come out, leave a line free on the dorsal 
side of the polypary. 
H.M.S. ‘Challenger,’ 
Manilla, January 1875. 
EXPLANATION OF PLATE XVIII A. 
All the figures give the natural size of the polypes. In fig. 1 the 
rhachis has been put in as seen by a low magnifying-power. Letters 
the same in all the figures :—r = terminal polypes; 1. and .= lateral 
polypes ; 111.= third lateral or fifth polype ; z = zooids. 
Figs. 1-4. Young stages of Umbellulariasp.?, found near the antarctic 
ice-barrier, lat. 62° 26’ S., long. 95° 44’ E., in a depth of 1975 
fathoms. 
Fig. 1. From the ventral side. Length 41 millims, 
Fig. 2a, from the ventral side; 26, from the dorsal side. Length 
52 millims.; length of polypes 7-83 millims. 
Fig. 3. From the ventral side. Length 100 millims., of polypes 11 millims. 
Fig. 4a, from the ventral side; 46, from the dorsal side. Length 
385 millims., of polypes 15 millims, 
