ERENNA REVISION 
the JSL 1688 specimen, occurring as enantiomorphic (mirror-im- 
age) pairs. The first type of bract (Fig. 10A, B), which measured up 
to 25 mm in length, was deeply incised on one side, at about its mid- 
length where a large flap was formed stretching across almost to the 
mid-line. On the other side, slightly proximal to this level, a small 
cusp was present. Toward the distal end, there were two further 
lateral cusps, with the one on the same side as the flap tending to be 
more marked than the other. The distal end of the bract was pointed. 
Close to the tip, the dorsal surface was thickened into an oval patch 
of cells that surround and were interspersed with over 200 
nematocysts, measuring c. 63 x 25 um. Another small patch of such 
cells was found on the dorsal surface of the bract, in the mid-line, 
and on a level with the lateral flap. That patch, at least, is believed to 
be a site of bioluminescence. Proximally, the bracteal canal origi- 
nated on the dorsal surface of the bract. It then curved over onto the 
ventral surface and continued distally in the mid-line. It appeared to 
be of variable thickness, but such variability was the result of 
variations in the thickness of the striated tissue that lay on each side 
of it. Close to the distal end of the bract the canal penetrated into the 
mesogloea and ended below the oval patch of epidermal cells. 
The second type of bract (Fig. 10C, D) was similar to the first, but 
tended to be shorter, up to 20 mm in length, and broader. The lateral 
flap, however, was much reduced, although still an obvious feature. 
Distal to this again there was an obvious lateral cusp; but on the other 
side the cusp was very small or absent altogether. The first type of 
bract was about three times more numerous than the second. Roughly, 
with over a thousand bracts and approximately 25 gastrozooids, 
there would seem to have been about 40 bracts per cormidium. Very 
young bracts (Fig. 10E) were roughly pyramidal in shape with the 
distinctive patch of epidermal cells, including nematocysts, fully 
developed. The bracteal canal was short and did not extend onto the 
dorsal surface; while beneath the distal patch of epidermal cells it 
formed an extensive cavity. 
GASTROZOOID. (Fig. 11A,B). The gastrozooids measured up to c. 
15 mm in length. The proboscis region, which often was curled back 
over itself, bore some stripes of gastrodermal cells. The stomach 
region, externally, was featureless and had a brown colour. The 
basigaster was greatly expanded on all sides, except that to which 
the tentacle was attached, and there was no obvious pedicle. 
TENTACLE AND TENTILLUM. (Fig. 12). Typically the annulated 
tentacle had a muscular lamella running down one side, with the 
tentilla attached on the other side, at the internodes. The tentilla were 
of an extraordinary design. Only in the very young tentilla (Fig. 12 — 
centre) was there any trace of a pedicle. In these the cnidoband was 
made up of a large saccus overlain by a horseshoe-shaped band of 
nematocysts. The terminal process actually arose from the base of the 
saccus and bore, towards its distal end, a pair of ‘ocelli’. The 
gastrovascular canal penetrated through the terminal process, but no 
connection with the saccus of the cnidoband could be discerned. As 
the tentilla matured the cnidoband lengthened, with the terminal 
process still only attached close to its base. The saccus diminished in 
importance and distally the band of nematocyst occupied all but a 
narrow strip of the external surface of the cnidoband. Proximally, 
where the terminal process was attached, the band of nematocysts split 
into two parts on either side of the saccus. Three types of nematocysts 
were present. The large anisorhizas, which measured c. 128 x 27 um, 
were arranged along the lateral margins of the cnidoband. Between 
them were numerous smaller nematocysts of two shapes, probably 
heteronemes, with the more cylindrical ones measuring c. 40 x 15 um 
and the more ovoid ones c. 32 x 18 um. Bands of musculature were 
present in the terminal process and extended distally to beneath the 
‘ocelli’. In life this process was reddish-brown in colour. 
7 

Fig. 11 Erenna laciniata. A., B. gastrozooids; C. palpon. Scale 2 mm. D. 
male gonophores. Scale 1 mm. 

Fig. 12 Erenna laciniata. Three mature tentilla (Scale 1 mm), with 
(centrally) an immature one (Scale 0.5 mm). 
PALPON. (Fig. 11C). Numerous palpons, up to c. 15 mm long, 
were present with the specimens. They were featureless thin-walled 
sacs filled, with a milky-white amorphous substance, although in 
life they were suffused with a brownish hue. The extent of the 
proboscis was variable, but typically, at its base, there were some 
