rg10.| J. Rrrcwm: Hvydroids of the Indian Museum. 25 
sharpest and the most pronounced, and an aperture lying at an angle 
of about 30° with the axis of the hydroclade. A stout intrathecal 
ridge, running backwards to the middle of the lumen, where it ends 
in an upturned thickening, marks the position of an anterior fold 
in the hydrothecal wall. Small chitinous points surround the open- 
ing through which the hydranth connects with the common ccenosarc. 
The mesial sarcotheca is very variable, its early stage, as seen in 
young colonies or on the distal ends of some hydroclades, closely 
resembling that of H. variabilis, Nutting (1900, p. 127, pl. xxxiii, 
fig. 7), for it stops considerably short of the intrathecal ridge ; while 
in its mature state it is adnate almost to the lip of the hydrotheca, 
projecting beyond the margin as a short free spout. Its most marked 
character in all stages is the concavity of its profile, and there is 
always present, more or less strongly developed, an internal chiti- 
nous projection almost on the level of the base of the hydrotheca. 
The supracalycine sarcothecee are small, not reaching to the margin 
of the hydrotheca, almost oval in outline, with a solitary wide 
superior aperture. The cauline sarcothecee are three in number, 
two on the stem anterior to the hydroclade and one posterior, almost 
in the angle above the hydroclade. In shape they resemble the 
supracalycine sarcothecee—none are bilobed, nor have any two 
apertures. 
Gonosome.—The gonangia, a funnel- or flask-like form of which 
has been described by Stechow (1907, p. 200; I909, p. 102, 
pl. vi, fig. 17), are present in numbers. They are unprotected and 
are borne on very short stalks, one at the base of each hydroclade. 
In shape they are saucer-like, convex beneath, concave above, and 
appearing as perfect disks when viewed from the anterior of the 
colony. 
Measurements. 
a 
| | 
Mature colony. Young colony. 
Hydroclade internode, length ae .. | 0°35—0'42 mm, | 0 39—0'43 mm. 
v 3 diameter at base ..| O°1I—O'I7 ,, | 007—O'IO ,, 
Hydrotheca, depth from base to highest teeth | 0°28—0'29 ,, | 0°25—0'27 ,, 
3 diameter of lower portion Pa | O214=——O- 15 ye OrL i Orl2 =, 
Re vertical diameter of mouth ..| 0°20—0o'2I ,, | O°17—oO'I8 
Gonangium, diameter of disk.. ae 55 | -upitoyorese yaaa. | 
Baa ea et. | A ee ee 
Locality: Andaman Islands, 1899; 60 fathoms. 
Distribution.—Previously recorded from ‘Torres Strait (Busk. 
1852: Kirkpatrick, 1890). 
Type of variety in the Indian Museum, Calcutta. 
Remarks.—This variety is distinguished from the typical form 
as figured by Bale, by the greater length of the thecate internodes 
compared with their diameter, the greater depth and more erect 
posture of the hydrothecz (to the former of which characters the 
name of the variety alludes), and the greater distance which separates 
the intrathecal septum from the base of the hydrotheca. The less 
