854: Prof, Allman on the Construction and 
Medusa at the time of liberation deep bell-shaped ; manubrium 
not reaching the orifice of the bell, and having its mouth sur- 
rounded by four short tentacles; radiating canals four, each 
terminating distally in a bulb, from which are developed two 
tentacles, each with a distinct ocellus at its base. 
Corynopsis Alderi, Hodge (sp.),=-Podocoryne Alderi, Hodge. 
The genus Corynopsis has been constituted for the Podocoryne 
Alderi of Mr. Hodge—a Hydroid, however, whose gonosome will at 
once separate it from the true Podocoryne. It will be noticed that 
the Medusa, at the time of its liberation, is not to be distinguished 
from that of Bougainvillia at the same stage of its development. 
The further progress of the Medusa of Corynopsis has not been 
traced ; but it is highly probable that we have here a true case of 
isogonism with Bougainvillia. 
4, Dipiura, Greene, MS. 
Trophosome.—Polypite supported on the summit of a simple 
hydrocaulus, with a branched and creeping (?) hydrorhiza ; 
periderm ?; tentacles filiform, in a single verticil (?) near the 
distal extremity of the body. 
Gonosome.—Gonophores phanerocodonie, on simple peduncles, 
which arise in a verticil from the body of the polypite at the 
proximal side of the tentacles. Medusa deep bell-shaped, with 
moderate-sized manubrium; radiating canals four, each termi- 
nating in a bulbous expansion at the point of intersection with 
the circular canal: from one of these marginal bulbs two long 
tentacles are developed; the rest of the margin is destitute of 
tentacles. 
The genus Diplura was originally, under the name of Diplonema, 
established by Prof. J. Reay Greene for a Hydroid of which the Me- 
dusa was alone known to him. (Nat. Hist. Rev. 1857, vol. iv.). The 
name of Diplonema, however, happened to be preoccupied by the 
botanist, and Prof. Greene has since substituted for it that of Di- 
plura. The Medusa thus named he found free in the open sea near 
Dublin; and it is undoubtedly congeneric with that described by 
Steenstrup as the Medusa of a Hydroid trophosome, which he names 
Coryne fritillaria. Steenstrup’s Hydroid, however, is certainly not 
a Coryne in the sense in which we must now understand this genus ; 
and though his description and figure are insufficient for an entirely 
satisfactory diagnosis, they compel us to regard his Hydroid as the 
representative of a distinct generic type, to which the name pro- 
posed by Prof, Greene for the Medusa, whose relation to Steenstrup’s 
form he recognized at the time of its discovery, must now be given. 
Agassiz refers it to Steenstrupia (Contr. Nat. Hist. U. 8S. vol. iv.) ; 
but the genus Steenstrupia was founded by Forbes for a Medusa of 
an entirely different type, though possessing unmistakeable affinities 
with Diplura. 
