REPOET ON THE HYDROIDA. 
o 
tion here adopted, we may safely regard the Kerguelen Hydroid as specifically identical 
with the European. 
Euclendrium rameum is eminently dendritic in its habit, and the tree-like disposition 
of its zooicls, in an assemblage which so forcibly recalls the physiognomy of some of the 
most characteristic forms of the vegetable kingdom, may well justify the appellation of 
“ zoophyte ” by which the Hyclroida have been designated in the writings not only of the 
earlier observers but in those of many zoologists of our own day. 
The Kerguelen specimen has a height of between 5 and 6 inches, and the fascicled 
stem has a diameter of nearly a quarter of an inch at its base. 
Family MONOCAULIDH1. 
Character of the Family. T ropliosome. — Tentacles filiform, in two sets, a proximal 
and a distal. Hydrocaulus solitary, naked. 
Gonosome. — Gonophores hedrioblastic. 
Monocaulus, Allman. 
Monocaulus, Allman, Ann. and Mag. Nat. Hist., May 1864. 
Generic Character. Trophosome . — Hydrocaulus solitary, naked. Hydranths abruptly 
distinct from the hydrocaulus, with a proximal and a distal set of filiform tentacles ; 
proximal set longer than the distal, and disposed in a single verticil near the base of the 
hydranth, the distal set scattered over a zone close to the summit of the hydranth. 
Gonosome . — Gonophores in the form of simple sacs borne upon peduncles which 
spring from the body of the hydranth between the proximal and distal sets of tentacles. 
The genus Monocaulus was constituted for the Corymorplia glcicialis of Sars, a form 
which, though its trophosome is that of a Corymorplia, is distinguished from that genus 
by the condition of its gonophores, which are adelocodonic, or in the form of simple 
closed sacs, instead of being as in every true Corymorpha phanerocodonic or rnedusi- 
form. 
Monocaulus imperator, Allman (PI. III. figs. 1-7). 
Monocaulus imperator, Allman, Narr. Chall. Exp., vol. i. p. 753, fig. 265, 1885. 
Trophosome . — Hydranth about an inch and a half in height, separated by a deep 
constriction from the hydrocaulus ; proximal tentacles about 4 inches in length, scarcely 
retractile, pendulous, about one hundred in number ; distal tentacles about half an inch 
in length, contractile, forming a dense fringe round the mouth, forty-eight or fifty in 
number. Hydrocaulus about half an inch in diameter, very extensile, and when fully 
extended many feet in height, marked by undulating longitudinal striae, nearly 
