M. C. Mereschkowsky on the Hydrotda. 329 
only the Medusz, but also the Hydroids, possess organs of 
sight. 
Oorhiza is always seated upon the shells of Gasteropods, 
especially Buccinum undatum and Fusus despectus, in large 
colonies, near the island of Solowetzky, most frequently at 
a depth of 5-8 fathoms. 
Prof. M. Wagner, who first found, examined, and figured 
it, has most kindly furnished me with all his facts and draw- 
ings, some of which are represented in Pl. XV. It is from 
these drawings that I have prepared the description of the 
Hydroid. 
Leptoscyphus Grigortewt, nov. sp. (Pl. XIV. figs. 1, 2.) 
A small branching colony. The branches which bear the 
hydrothecee with their pedicels are regularly and slightly 
angularly bent and slightly ringed, especially above each angle. 
The pedicels which support the hydrothece are short, never 
exceeding half the length of the hydrotheca, and are much 
more strongly ringed than the branches. They are very 
regularly arranged alternately upon the branches, and always 
issue from the angle formed by the branch. The hydrothece 
are of an elongated form, in the shape of two cones, of which 
the inferior is the larger, and the upper, smaller one is divided 
into lobes, which form an operculum; this division is not 
deep, never exceeding 4 of the length of the whole hydro- 
theca. 
The gonophores are unknown. 
Locality.—The colonies were found seated upon an Ascidian 
which is very widely distributed in the White Sea, in the Bay 
of Onega, at the mouth of the river Kem, in 34° 55’ of longitude 
at a depth of 5 fathoms, on a muddy bottom, July 5, 1875. 
The position that I have assigned to this Hydroid, in the 
genus Leptoscyphus, is only provisional; it might equally 
well be placed in the genus Campanulina, which only differs 
from Leptoscyphus in the gonophores, with which I am un- 
acquainted here. In regard to its specific distinctness, there 
ean be no doubt that the Hydroid in question constitutes a 
new species, which I have called Leptoscyphus Grigortew?, in 
honour of my travelling companion, the botanist, A. W. 
Grigoriew. 
This species is distinguished principally by the form of 
the hydrothece, which have the segments of the superior 
cone not very deep, usually less than one third of the total 
length of ithe hydrotheca. ‘This distinguishes it from L. tenuis, 
Allman, with which it has many resemblances. The lower 
part of the hydrotheca narrows regularly (Pl. XIV. fig. 2, d) ; 
Ann. & Mag. N. Hist. Ser. 5. Vol. 1. 22 
