Limitation of Genera among the Hydroida. 875 
sibility of the polypites, and their power of complete retraction into 
hydrotheca-like receptacles, would seem to indicate that the affinities 
of Trichydra are rather with the Campanularian than with the 
Tubularian Hydroids. 
Trichydra pudica, Wright. 
7. Catyceita, Hincks. 
Trophosome.—Hydrocaulus erect, and rooted by a filiform 
hydrorhiza, or creeping and adherent; hydrothece tubular or 
conical, and provided with an operculum which is formed of 
converging lanceolate segments. Polypites cylindrical, with the 
tentacular verticil surrounding the base of a conical metastome. 
Gonosome.—Gonophores adelocodonic. Sporosaes of female 
ultimately delivering their contents into an acrocyst. 
The genus Calycella was founded by Hincks (Ann. Nat. Hist. 
Oct. 1861) with the intention of including under it certain Hydroids 
previously placed under Campanularia’ and Laomedea. Calycella, 
however, as constructed by Hincks, really involves two distinct types, 
one of these being represented by Calycella dumosa, Hincks (gen.), 
and the other by Calycella syringa, Hincks (gen.). 
Now the C. dumosa belongs to a form which had been already 
defined by Lamouroux under the name of Lafoea, a name, therefore, 
which the rule of priority obliges us to leave undisturbed; and the 
name of Calycella must accordingly be retained for the remaining 
type alone—that represented by the Campanularia syringa of au- 
thors, and by the Campanularia lacerata of Johnston. 
Calycella syringa, Linn. (sp.),= Campanularia syringa, Lamk., 
= Clytia syringa, Lamx., = Campanularia syringa, Van Ben., = 
Wrightia syringa, Agass. 
Calycella lacerata, Johnst. (sp.), = Campanularia lacerata, 
Johnst.,= Wrightia lacerata, Agass. 
Calycella? humilis, Hincks. 
8. CaAMPANULINA, Van Beneden. 
Trophosome.—Hydrocaulus branching or simple, attached by 
a creeping filiform hydrorhiza; hydrothece with their margin 
continued by a delicate collapsible membrane [or else provided 
with a true operculum formed by converging lanceolate seg- 
ments]. Polypites cylindrical ; tentacula connected by a mem- 
branous web at their base. 
Gonosome.—Gonophores phanerocodonic. Medusa, at the time 
of liberation, deep bell-shaped, with moderate-sized four-lipped 
manubrium ; radiating canals four, each terminating distally in 
anon-ocellated bulb ; marginal tentacles two, developed from two 
opposite bulbs [or four, every bulb then carrying a tentacle] ; 
lithocysts eight, two in each interradial marginal space. 
