Prof. Allman on the Hydroida. 59 
imperfect verticil of three or more. Between the medusa of the 
various species of Bougainvillia whose trophosome has been 
observed I cannot discover any difference which could be ad- 
vantageously employed in the diagnosis. 
Heterocorpyte, Allman *, 
Gen. char.: Trophosome.—Ccenosare consisting of a simple or 
branched hydrocaulus, which arises from a creeping filiform and 
anastomosing hydrorhiza, the whole invested by a chitinous peri- 
derm. Polypites fusiform, with a single verticil of filiform ten- 
tacula round the base of a conical metastome. 
Gonosome.—Gonophores adelocodonic, borne by gonoblastidia 
which are developed (solely ?) from the hydrorhiza ; sporosacs 1n 
the form of simple fixed sacs destitute of tentacles and cilia. 
Species unica: H. Conybearei, Allman. Plate II. 
Trophosome.—Hydrocaulus consisting of numerous much- 
branched stems, along with short simple ones, all crowded on the 
creeping hydrorhiza, the longest stems attaining a height of 
about four lines; periderm transversely corrugated, slightly 
dilated at the base of the polypites, ash-brown. Polypites with 
about twelve tentacula, usually held straight on extension, with 
the alternate ones depressed when partially contracted, the tenta- 
cles present a slightly clavate outline at their extremities. 
Gonosome.—Gonoblastidium springing out of a short tubular 
process from the upper surface of the hydrorhiza, club-shaped, 
its distal extremity thickly set with thread-cells; gonophores 
numerous, on very short peduncles, densely crowded, commen- 
cing a little behind the distal extremity of the gonoblastidium, 
and thence extending to within a short distance of its base. 
H. Conybearei was obtained last autumn in considerable abun- 
dance in the Harbour. of Glengariff, co. Cork, investing old 
univalve shells which had been taken possession of by hermit 
crabs. In habit it exactly resembles Dicoryne conferta, and with- 
out the aid of a microscope might be easily mistaken for this 
species ; but the structure of the gonophores, which are simple 
sporosacs, entirely resembling those of Clava, must remove it by 
a wide interval from Dicoryne. 
I have much pleasure in calling the present species after an 
ardent and scientific worker with the microscope, a member 
of a family whose name is already inseparably united with the 
progress of natural science in these islands, Henry Conybeare, 
Esq., in whose company, during a dredging-expedition in the 
* T have already given in the Synopsis a diagnosis of this genus, unac- 
companied, however, by a figure or by a description of the only known 
species. 
