314 Proceedings of the Royal Physical Society. 
Fig. 4. Sacculina triangularis ; external skin and corium reflected : a, external 
skin covered internally by the corium ; i, ovigerous lamella3. 
Fig, 5. Ovigerous sac, showing the anterior and posterior folds which embrace 
the internal ovaries. 
Fig. 6. Mass of ova from the ovigerous lamellse. 
Fig, 7. Greatly magnified view of one of the vesicles, drawn from a fresh 
specimen : a, the duct of the vesicle ; c, the structure found in the 
interior of the vesicle ; h, the horny substance found at the com- 
mencement of the duct. 
Fig. 8, The same organ as fig. 7, drawn from a specimen preserved in alcohol : 
a, the convoluted duct ; 6, the horny process. 
Fig. 9. The structure found in the interior of the vesicle, removed. 
Fig.. 10. Sacculina carcini, with no ovigerous lamellje, nat. size : 6, the 
peduncle ; b', intestine of crab ; c, ovario-branchial orifice. 
Fig. 11. Sacculina triangularis, nat. size. (Same references as in fig. 10.) 
Fig, 12. >S'. carcini distended with ova. 
Fig. 13. Posterior view of fig. 12 ; d, horny attachment of peduncle ; k, pro- 
longed portion of the same. 
Fig. 14. A group of ;S'. triangularis. 
Fig. 15. S. inflata (after Leuckart). 
Fig. 16, Enlarged view of the vesicles of S. carcini. 
II. Observations on British Zoophytes, 1. Hydractinia areolata, n. sp. 
2. Atractylis arenosa, 7i. sp. (Plate XIV.) By Joshua Alder, Esq. 
Communicated by T. Strethill Wright, M.D. 
1. Hydractinia areolata., n. sp. Plate XIV., figs. 1-4, 
Polypary encrusting, consisting of a solid chitinous ex- 
pansion, from which arise simple linear spines in irregular 
groups, leaving areolar spaces between them. Polyps 
naked, small, white, columnar, slightly enlarging above, 
and terminating in a conical mouth, below which is a single 
circle of from six to ten linear tentacles, appearing of dif- 
ferent lengths from their varying contractility. Gono- 
phores (reproductive organs) sessile on the chitinous base, 
large, globular, or slightly pear-shaped, containing each a 
single medusoid. Height of polyp about tV th inch. 
Medusoid with a moderately deep subglobose umbrella, 
having four golden-yellow radiating canals, at the bulbous 
bases of which, on the margin of the umbrella, are four 
rather short tentacles ; four shorter ones alternate with 
them ; and intermediate between these are eight others, 
almost tubercular. The peduncle is rather long and co- 
