CATALOGUE OF THE ZOOPHYTES, ETC. 225 
XXXVI.—Supplement to a Catalogue of the Zoophytes of North- 
umberland and Durham. By Josuua ALDER. 
Crass. ANTHOZOA, Ehrenberg. 
OrpEeR. HYDROIDA, Johnston. 
Famity. TUBULARIADA, Van Beneden. 
8. HYDRACTINIA, Van Beneden. 
2. H. arnouaTa, 2. sp. Pl. IX., fig. 1—4. 
Polypary encrusting, consisting of a solid chitinous expan- 
sion, from which arise simple linear spines in regular 
groups, having areolar spaces between them. Polypes 
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 different lengths from their varying contractibility. 
Gonophores (reproductive organs) sessile on the chitinous 
base, large, globular or slightly pear-shaped, containing 
each a single medusoid. Height of polype about +, of 
an inch. 
Medusoid, with a moderately. deep, sub-globose 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 four others, 
almost tubucular. ‘The peduncle is rather long and col- 
umnar, with four tufts of thread-cells surrounding the 
mouth. 
A single specimen only of this interesting little Hydractinia 
was obtained, parasitical on a dead shell of Natica Alderi, brought 
in by the fishing boats at Cullercoats. I have since seen a dead 
and rather worn specimen, upon Natica Grenlandica, among the 
zoophytes collected in Shetland by the Rev. A. M. Norman. 
The species differs from H. echinata in its much smaller size, the 
simple linear form of its spines, their irregular grouping, and 
