ERENNA REVISION 

Fig. 15 Erenna cornuta. A. Three bracts of first type; B. two bracts of 
second type. Scale 2 mm. 
radial canals passed through the middle of the muscle-free zone to 
reach the apex of the nectosac just short of its lateral margins. At 
that point the narrow ‘horn’ canals may or may not be given off. 
When present these ‘horn’ canals extended up for a variable dis- 
tance, toward the apex of the nectophores, typically terminating 
on a level with the central thrust block. Eight nectophores (Fig. 
14A, B) had well-developed ‘horns’, as did the two immature 
ones (Fig. 14D). In three others the ‘horn’ canals were ill-defined 
and short; while in the remaining two (Fig. 14C) there was no 
trace of them whatsoever. 
The mature nectophores varied slightly in shape apparently in 
association with the extent of the ‘horn’ canals. The tapering axial 
wings were more extensive on those with well developed ‘horn’ 
canals; while the central thrust block typically was slightly smaller 
than those without ‘horn’ canals. The ones with ill-defined ‘horn’ 
canals tended to be intermediate. Of the 23 damaged nectophores 
collected at Discovery St. 7856#54 the ‘horn’ canals were prominent 
in all but the two smallest, but mature ones. The others were larger 
than the JSL II Dive 1451 ones, measuring c. 20 mm in length and 
width, and had denser musculature on the nectosac. The ‘horn’ 
canals also were more extensive, and there were traces of orange- 

Fig. 16 Erenna cornuta. A. gastrozooid, and B. palpon. Scale 1 mm. 
179 
brown pigment in the basal parts of the radial canals and, particu- 
larly, the ostial ring canal. 
BRACTS. (Fig. 15). Two types of bract were present; the first (Fig. 
15A), and considerably more numerous, being longer, up to 16 mm 
in length, and narrower than the second (Fig. 15B), which was up to 
10 mm in length. Both types possessed a pair of lateral cusps. In the 
first type, as was the case with Evenna richardi, these seemed to lie 
at a fixed distance from the proximal end of the bract, and were 
asymmetrically disposed. Along the axis between these two cusps, 
on the dorsal surface of the bract, there was a rounded transverse 
ridge or process, that marked a change in the thickness of the bract, 
which was thinner distally. This ridge did not connect with the cusps, 
and its extent and distinctiveness was variable. Just distal to the 
ridge, in the mid-line, there was a small patch of cells; although often 
these has been abraded away. 
On the second type of bract the lateral cusps were positioned, 
almost symmetrically, at about the mid-length of the bract. Just 
distal to these cusps there was a more or less pronounced cross-ridge 
which again demarcated a change in the thickness of the bract. 
Again a small patch of cells was situated distal to this ridge, in the 
mid-line. On the distal half of both types of bract, there could be an 
additional lateral protuberance of variable shape. At the distal tip of 
both types the dorsal surface was raised up in the mid-line to form an 
elongate or elliptical process on which were found a concentration 
of small epidermal cells, with brownish-red pigment. Centrally, 
these cells included some nematocysts, which measured c. 68 x 
32 um. 
The bracteal canal originated, proximally, slightly over on the 
dorsal surface of the bract. It passed down the middle of the bract in 
close contact with its ventral wall, with striated bands of cells lying 
on either side of it, indicating where the muscular lamella was 
attached. At some distance from the distal end of the bract, in 
comparison with Erenna richardi, the canal penetrated into the 
mesogloea and curved up to end beneath the proximal part of the 
concentration of cells on the dorsal surface. 
GASTROZOOID. (Fig. 16A). Only three well-developed gastro- 
zooids remained with the specimen. The largest was 6 mm in length. 
The basigaster formed a horseshoe-shaped, laterally expanded struc- 
ture around the base of the gastrozooid, with the tentacle attached in 
the open zone. It was a light brown colour. No obvious pedicle. The 
expanded stomach was externally featureless and had a dark brown 
colour. The proboscis region, which was about the same length as 
the stomach, had distinct stripes. 
TENTACLE AND TENTILLUM. (Figs 17, 18). The tentacle was annu- 
lated, with a muscular lamella running down one side, and the 
tentilla attached, on the opposite side, at the internodes. There were 
two types of tentilla, both of which were found attached to the same 
tentacle. Early on in the development of the first type (Fig. 17A), the 
tentillum consisted of a long pedicle and a minute cnidoband devoid 
of nematocysts. The gastrovascular canal was seen, at the end of the 
pedicle, to turn back and continue down to open into the cavity of the 
saccus of the cnidoband. With further development the connection 
with the saccus cavity was closed, and the cavity filled with 
gastrodermal cells. A remnant of the diverticular canal seemed to 
persist, passing through a relatively dense band of gastrodermal 
cells. In the mature tentillum (Fig. 17B), the proximal part of the 
pedicle was expanded, typically tapering towards its base. The 
gastrovascular canal could occupy most of the interior, or could 
remain as a narrow tube, which became twisted and folded up on one 
side of the pedicle. Distally the pedicle was narrower, with the canal 
often having a zigzag appearance, probably indicating some 
