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 seen the 

 egg in process of development in individuals unprovided with 

 the sperm-vesicles. 



It is worthy of 1 em ark, 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 observations, however, are required 

 to settle this point. 



I have also observed sperm-vesicles, PI. VII. fig. 6, in H. 

 viridis : in this species they are much smaller than in the speci- 

 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 irregularly 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, Pis. VI. & VII. 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 



