found in the Northumberland Lakes. 285 
The male organ is only developed at the time the eggs make 
their appearance. In August, shortly after the polypes were 
procured, they multiplied rapidly, as we have seen, by gemmation, 
and at this period none of the sacs containing spermatozoa were 
observed. It was not until they had ceased to propagate in this 
way, some time in September, that the male organ was developed, 
and it was always visible afterwards, though variable in size. 
All the individuals apparently produce eggs, and all are alike 
provided with the spermatic sacs; at least the ovum in various 
stages of development and the male organ are seen at the same 
time in most specimens: it is not uncommon, however, to ob- 
serve the male organ only, the egg probably having just left the 
body of the parent, though I do not recollect having scen the 
egg im process of development i in individuals unprovided with 
the sperm-vesicles. 
It is worthy of 1emark, that the buds sprout from the same 
part of the body in which the eggs are developed; but I have 
seen nothing to warrant the assertion that the ova after im- 
pregnation “sometimes are retained and then grow out like 
buds.” Indeed it is probable that fecundation does not take 
place until the egg bursts through the integument, and is attached 
to the parent only by a delicate pedicle. This would appear more 
likely than that impregnation should be effected through the 
skin of the animal. Whilst watching an individual when the 
egg was about to separate from the parent, the sperm-vesicle was 
frequently brought, by the contractions of the body, almost in 
contact with the ovum; thus fecundation might very easily be 
effected, and at a moment, too, when from analogy it might be 
expected to take place: more obser vations, however, are required 
to settle this point. 
I have also observed sperm-vesicles, Pl. VII. fig. 6, in H. 
viridis: in this species they are much smaller than in the spect- 
mens from the Northumberland lakes, and are generally two or 
three in number, near the anterior extremity of the body, but 
without symmetrical arrangement. They are irregular.y conical, 
with the base wide, within which there is likewise a distinct 
glandular body of a green colour; the moving bodies are very 
numerous, and occupy, as in the other species, the transparent 
apex. The sperm-vesicles were noticed in H. viridis after it had 
ceased to bud, some time early in October. 
The tentacles, Pls. VI. & VIL. figs. 5, 7, of the flesh-coloured 
species are very rough and beautiful, exhibiting an imperfect 
spiral arrangement of the nodular enlargements. There are two 
kinds of vesicles immersed in the nodules, as have been described 
in some other species; one being much more numerous and 
smaller than the other. The former are for touch, the latter for 
