ERENNA REVISION 
Fig. 5 Erenna richardi. A. and B. Gastrozooids; C. and D. palpons; E. 
Immature gonodendron. Scale 2 mm. 
The bulk of the saccus was made up of a thick layer of transparent 
gastrodermal cells which formed a characteristic reticulate pattern 
(Fig. 6), through which the narrow, dark (black in life) pigmented 
gastrovascular canal (Fig. 7gvc) passed. In many preserved tentilla 
this canal was damaged. Figure 6 shows an undischarged and a 
discharged tentillum. 
The numerous nematocysts formed a dense, darkly pigmented 
cnidoband, the sides of which undulated irregularly. On the mature 
tentillum the distal end of the cnidoband hung free from the main 
body. Three types of nematocysts were present. On the sides there 
were rows of larger ones, probably homotrichous anisorhizas, meas- 
uring c. 165 x 32 um. Between these were numerous smaller 
nematocysts of two types, one measured c. 43 x 15 um, the other c. 
27 x 20 um. No discharged nematocysts of these types were found, 
but probably they were both atrichous haplonemes, as Margulis 
(1977) suggested, although she noted only one type. 
The rigid terminal process (Fig. 6) was up to c 10 mm in length 
and devoid of nematocysts. The gastrovascular canal passed through 
it, ending close to its distal extremity. Just proximal to the end of the 
canal it branched off a diverticular canal (Fig. 7dc) that passed back 
through the terminal process to end below the distal part of the 
cnidoband. As Bedot (1904) noted there was a band of longitudinal 
musculature on each side of the terminal process. Overlying the 
lateral sides of the diverticular canal, close to its point of origin, 
there was a pair of brownish-white oval structures (Fig. 70) com- 
prised of distinctive epidermal cells. Lens & van Riemsdijk (1908) 
aptly called them ‘ocelli’, as is discussed below. 
As noted above it was the distal end of the cnidoband that hung 
free from the main body of the mature tentillum. However, on the 
young, developing tentillum (Fig. 7A), the cnidoband formed a 
triangular process that was slightly undercut on its proximal surface; 

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with the pedicle and terminal process being only slightly developed. 
The axial and diverticular canals were prominent, and the latter 
opened into the saccus of the cnidoband. With further development, 
the saccus became closed off and began to fill with gastrodermal 
cells (Fig. 7B). The cnidoband remained undercut proximally. With 
further elongation of the tentillum (Fig. 7C, D), the proximal part of 
the cnidoband began to fuse with the saccus, and the ‘ocelli’ on the 
terminal process were developed, while the canal system narrowed. 
Finally, the distal end of the cnidoband became detached from the 
saccus. 
PALPON. (Fig. 5C, D). Up to 15 mm in length, with a palpacle 
attached at the base of the pedicle. Brown (black in life) pigment 
throughout. Pedicle with reticulate pattern of cells. Main stomach 
region with an irregular pattern of patches. Distally these were 
concentrated to form 12-14 vertical stripes, with denser pigmenta- 
tion, surrounding the base of the proboscis with its terminal opening. 
No obvious nematocysts present on the palpacle. 
GONODENDRA. (Fig. 5E). Only female gonodendra were found on 
the JSL II 1456 specimen. Mature female gonodendra were com- 
prised of small, tightly packed bunches of c.20—25 gonophores, with 
a milky brown coloration, connected to a relatively short stalk. Each 
gonophore measured c. 0.45 mm in diameter and contained a single 

Fig. 6 Erenna richardi. Photographs of tentilla (c. 25—30 mm in length) 
before (A.) and after (B.) discharge of nematocysts. 
