360 Prof. Allman on the Construction and 
only with its termination altered so as to adapt it to the ordinary 
form of zoological nomenclature—a form in which Dujardin’s name 
has been used by most subsequent writers, as Krohn (Miiller’s Arch. 
1853) and Gegenbaur (Zeit. f. w. Z. 1857, p. 230). 
Dujardin and the writers who have followed him have given this 
name to a Hydroid whose trophosome is distinguished by the cha- 
racters here enumerated ; but as it has been shown by Hincks (Ann. 
Nat. Hist. Dec. 1862) that this form of trophosome may have two — 
very different forms of gonosome, it is necessary to break up Dujar- 
din’s genus into two, one of which may retain his original name for 
the trophosome, while to the other we may give the name of Clado- 
nema, that employed by Dujardin for the only form of Medusa which 
he succeeded in tracing to a Stauridioid trophosome. 
Stauridium productum, Wright. 
5. Cuaponema, Dujardin. 
Trophosome.—Ceenosare consisting of a branching or simple 
hydrocaulus arising from a creeping filiform hydrorhiza, the 
whole invested by a chitinous periderm. Polypites borne on the 
summits of the hydrocaulus, clavate, with two verticils of tenta- 
cles, each verticil consisting of four tentacles disposed in a cross, 
—the tentacles of the proximal verticil filiform, those of the 
distal verticil capitate*. 
Gonosome.—Gonophores phanerocodonic, developed from the 
body of the polypite. Umbrella deep bell-shaped; manubrium 
large, with simple mouth ; radiating canals eight, each continued 
at the margin of the umbrella into a branching tentacle with a 
bulbous base provided with an: ocellus. 
Cladonema radiatum, Dujardin. 
6. Pennants, Goldfuss. 
Trophosome.—Ccenosare composed of a symmetrically ramified — 
hydrocaulus, rooted by a creeping filiform hydrorhiza, the whole 
invested by a chitinous periderm. Polypites borne on the sum- 
mits of the branches, oviform, with two sets of tentacles—a 
proximal set filiform and arranged in a single verticil round the 
base of the polypite, and a distal set capitate and scattered on 
the body of the polypite. 
Gonosome.—Gonophores phanerocodonic, developed between 
the proximal and distal set of tentacles. Umbrella deeply ovate ; 
manubrium large, but not passing beyond the orifice of the — 
* Tt will be noticed that the above description of the trophosome of 
Cladonema is identical with that of the trophosome of Stauridium. The 
differences between the two genera are confined to the gonosome, where 
they are well marked. 
