British Hydrozoa, Actinozoa, and Polyzoa. 83 



the body, filiform tentacula are scattered. The gonophores are 

 in the form of mulberry-like masses, at first sight apparently 

 sessile, but really upon very short gonoblastidia, which are 

 situated in openings in the creeping base of the hydrozoon. 



Tubiclava Cornucopia was dredged in from 80 to 100 fathoms, 

 about twenty miles north of Unst in Shetland, and was parasitic 

 on the shells of Astarte sulcata and Dentalium Entalis. It is 

 worthy of remark, that in every instance the hydrozoon was ob- 

 served upon shells still occupied by the living Mollusca, and 

 that it invariably had assumed a position at the posterior ex- 

 tremity of the shell, where it would receive the benefit of the 

 aqueous currents caused by the mollusk, which, while providing 

 for its own necessities, thus unwittingly performed the kindly 

 office of feeding its hungry neighbour. 



The genus in which this undescribed form is placed was esta- 

 blished by Professor Allman in the ' Report of the British Asso- 

 ciation 'for 1863. * 



Fam. Tubulariada. 



Genus Eudendrium (Ehrenberg). 



Eudendrium annulatum, n. sp. PI. IX. figs. 1-3. 



E. fruticosum ; ramis majoribus crassis, coalescentium fistularum 

 insolito reticulo obductis ; ramulis numerosissimis, brevibus, passim 

 distincte (sicut iu Coryne ramosa) annulatis ; polypis calices non 

 expanses obsidentibus, tentaculis 1 6-20 prseditis ; gouophoris 

 uvarum formam simulantibus, in gonoblastidiis positis. 

 Hydrozoon quatuor poUices attingit. In freti " Burrafirth " cavemis 

 apud insulas Zetlandicas vitam degit. 



This Eudendrium grows to a height of about 4 inches, and is 

 seen at a glance to diff^er from its congeners E. rameum and E. 

 ramosum in its more shrubby and dense habit. The main stems 

 are very thick and strengthened with a curious network of ana- 

 stomosing tubes on their surface (PI. IX. fig. 3). The smaller 

 branches are closely and regularly ringed in every part (fig. 3), 

 and are excessively numerous. The tubes are not expanded at 

 their extremities to receive the polypites, as is the case in some 

 allied species. The polypites are furnished with from sixteen to 

 twenty tentacles. The gonophores are grouped in clusters, 

 consisting of eight to twenty egg-shaped bodies attached round 

 the axis of gonoblastidia, which are of moderate length. 



Eudendrium is a difficult genus ; but the present species appears 

 to be very distinct from the seven British forms which have 

 hitherto been described. It was found in a cave, known as 

 " Buness Hall,'' which is one of many caverns, all remarkably 

 rich in animal life, which penetrate the cliffs on the eastern side 

 of Burrafirth, the northernmost of the voes of Shetland. It was 



6* 



