TQIO. | J. Rrrcw1e: Aydroids of the Indian Museum. 13 
Diphasia thornelyi,' Ritchie. 
(Biv iv sires. 58) 
Ritehie Ji, 71909 (2)5 p:.525: 
Several delicate, unbranched colonies, with non-fascicled stems 
were found growing about the ‘‘ root’’-masses of Lytocarpus 
pennarius. ‘They are small (the largest only 16 mm. high), spring 
from a simple stolon, show no traces of nodes, and bear hydrothecze 
from the base upwards. The hydrothecee vary much in their posi- 
tion relative to one another. ‘They are biserial and lie in the same 
plane, and although in most cases they are alternate or sub-alternate, 
rarely an opposite arrangement is simulated. 
A hydrotheca is deep and narrow, with the inner edge adnate 
to the stem for practically its whoie length, except for a short 
horizontal knobbed ledge upon which the adcauline operculum is 
hinged. The cavity of the hydrotheca is divided into two parts 
by a short upturned ridge which projects from the abcauline wall 
midway between the base and margin. Proximal to this hooked 
intrathecal ridge the wall of the hydrotheca suddenly becomes much 
thicker (up to 60 »), and is continued thus till the next hydrotheca 
is reached. The outer wall of the distal half of the hydrotheca 
curves gently outwards and upwards, and almost parallel to the 
outer wall, and terminating at the base in a thickened ridge, runs 
the partition which separates the cavity of the hydrotheca from 
that of the stem. The margin is smooth and rimmed, a border 
being formed by a well-marked line which runs parallel to the lateral 
edges of the hydrotheca. The aperture, which faces somewhat 
towards the stem, forms an arc of a circle, its outer border being 
rounded, while its adcauline side, bounded by the horizontal ledge 
on which the operculum rests, is straight. The distal portion of 
the hydrotheca, as a whole, assumes the appearance of a bracket 
projecting from the stem. The operculum is a single, strong, ad- 
cauline disk, which rests on a thickened ledge. 
Gonosome.—The gonothece arise from immediately beneath 
the hydrothece, and are without stalks. They are ovate in shape 
but are somewhat asymmetrical, a bulge occurring on the shoulder 
towards the stem. The aperture is cylindrical, placed on a short 
neck, and the distal half of the gonangium is ornamented with 
scattered but prominent spines. 
Measurements. 
Hydrotheca, length oe or .. 0°38—0'45 mm. 
a breadth m es 2) O'LI—O TAs > 
a diameter of aperture from 
side to side a a OT we 
Gonangium, length 3 oe, 3h OH Gy h es 
= maximum diameter 5 O27 
1 This species has been named in honour of Miss Laura R. Thornely whose 
paper on the Hydroids collected by Professor W. A. Herdman off Ceylon has 
added much to our knowledge of the Indian members of the group. 
