HYDROIDA. 
459 
C. ? dumosa, Flem. 
On Tubularia indivisa at Youghal, 1836, Miss Ball. 
On Serialaria lendigera and various corallines in Belfast Bay, W. T. 
Dublin Bay, Dr. Ball, Sept., 1839. Bootle coast, Liverpool, from Mr. 
Henry Johnston. Adherent to a stone from Strangford. Dredged in 
about 40 fathoms water at Sana Island, by Mr. Hyndman, parasitic on 
Thuiaria articidata. Youghal, Miss Ball. Parasitic on various zoophytes ; 
among others I have seen the delicate Serialaria lendigera covered with its 
tubes. Invests the upper portion of shells of the Dentalium entalis, dredged 
with the animals living in Strangford Lough, July, 1838, W. T. 
C. verticillata, Lamx. 
Found commonly thrown ashore at Portmarnock, in 1835, and subse- 
quently more rare, but of occasional occurrence in deep water in Belfast 
Bay, W. T. Magilligan, Mr. Hyndman. Courtmasherry Harbour, Prof. 
Allman, W. T. 
C. integra , Macgill. 
North of Ireland. 
Genus Hydra. 
H. viridis, Linn. 
East and South of Ireland. 
Obtained at Bandon (Co. Cork), by Prof. Allman. 
H. vulgaris , Pall. 
North, East, and South of Ireland. August 20, 1846, I saw in a 
glass globe — such as gold fish are kept in — half filled with water, in 
Mr. Hyndman’s house, about twenty living Hydrce, which were ob- 
tained by him in May last, from the pond in the Zoological Gardens, 
Dublin, a locality previously known by Mr. Callwell as frequented by 
the species. Not one of these specimens showed any attenuation below, 
and hence are not II. attenuata or LL. oligactis. The tentacula are not 
“ shorter than the body,” hence they are not H. viridis. They were 
longer than the body and six in number in all the specimens, as I saw 
them displayed. The colour of the body is a very pale reddish-brown. 
When the body is fully extended, nearly 6 lines long, or 5 lines certain. 
The tentacula are of about the same length, but when not so (and this 
was the case in all but one specimen) they were considerably longer (5 
lines). 
Hydra. See Johnston’s Zoop., p. 131, 2nd edit. Effect of, on Limneus 
pereger — Sept. 1846. Mr. Hyndman observing a Limneus moving towards 
a Hydra fixed on the side of a glass globe half filled with water, remarked 
that the moment the tentacula of the Limneus touched the arms of the 
Hydra, the Mollusc suddenly drew back and changed its course. The 
Hydra did not draw in its arms. On a subsequent occasion, Mr. Hynd- 
man observed a Planorbis marginatus (under half size) moving towards a 
Hydra, and on coming in contact with its body, the Mollusc was not affect- 
ed, but endeavoured to move onwards, at risk of displacing the Hydra ; 
this species, however, kept its ground, and the Planorbis moved off in the 
direction of its arms, which were no sooner touched than it also, like the 
Limneus, suddenly drew back, and moved in another direction. The re- 
