308 HETEROCORYDLE CONYBEAREI. 



Colour. — Ash brown. 



Beveloj)Ment of Gonosome. — Observed in September. 

 Habitat. — On old univalve shells in the sea. 

 Bathymetrical distribution. — Laminarian and coralline zones. 



Localities. — GlengarifF Harbour, County of Cork, G. J. A. ; Oban, Argyieshire, Rev. T. 

 llincks. 



This very distinct hydroid, the only representative as yet discovered of its genus, was dredged 

 in considerable abundance from a rather muddy bottom in the Harbour of Glengarifi', on the 

 south coast of Ireland. It was always found investing old gasteropodous shells, whose cavity 

 was in every instance tenanted by a hermit crab. It so closely resembles Dieori/iie conferta in 

 form, colour, and general habit, that it was at first mistaken for this species, and it was only the 

 closer inspection of its gonosome which showed how very widely it differed from it. 



Ileterocordyle Coni/bearei spreads itself in the form of a dense moss-like covering over the 

 shell of which it has taken possession, extending in all directions by means of a reticulated 

 stolon, which sends up at short intervals the stems of the trophosome and the blastostyles of the 

 gonosome. The stems are for the most part well developed, and much, but rather irregularly, 

 branched, while a few simple and much shorter stems, each carrying a hydranth on its summit, 

 spring here and there from the creeping base. The tentacles, when extended, are held alter- 

 nately elevated and depressed, indicating a composition of the tentacular circlet out of two closely 

 approximated verticils. When partially contracted the tentacles frequently present a slight 

 enlargement of their extremities, giving them a somewhat clavate form. The perisarc extends 

 for a very short distance over the base of the hydranth, and then terminates aliruptly by a 

 defined edge. 



The blastostyles are liorne on the summits of very short stalks, which spring like the stems of 

 the trophosome from the creeping stolon, and which, like them, are also invested with a chitinous 

 perisarc. The blastostyles are clavate, but as they admit of considerable extension and con- 

 traction their form is a varying one. Their distal extremity is rounded, and thickly set with 

 thread-cells. 



The gonophores spring from the sides of the blastostyle, to which they are attached by 

 peduncles so short as to render them almost sessile. They are crowded upon the blastostyle, a 

 short space at its distal extremity and another at its proximal being the only parts free from 

 them. They are oviform and constructed on the type of the simple fixed sporosac ; the 

 spadix is large, and in the female embraces a large solitary ovum, over which the endotheca 

 extends as a well-marked layer, while a very distinct cctotheca, in which no evident structure can 

 be detected, envelopes the whole. 



The male gonosacs resemble the female in form, and in the mode in which they are 

 grouped upon the blastostyle. The spermatogenous mass is developed round the spadix, and 

 is confined by an exceedingly delicate investing membrane (endotheca), while the whole is 

 surrounded by a distinct but apparently structureless ectothecal sac. 



It was in company with an accomplished microscopist, Henry Conybeare, Esq., during a 

 dredging excursion in the beautiful Bay of Glengariff that this remarkable hydroid was first 

 obtained, and I have yielded to the gratification of dedicating it to my friend, and thus connecting 

 it with the name of a family to which the progress of natural science is largely indebted. 



