75 
Finally it may be added, that in those specimens of Hippolyte in whose branchial 
cavity was found an adult female with ovisacs of Choniostoma, the gills belonging to the 
two foremost pairs of trunk-legs were either somewhat reduced, or had quite disappeared, 
and in one case the three other gills situated more behind appeared a little curled, as a 
sign of degeneration. In one specimen, which was infested with several smaller females, 
the gills were slightly curled. 
i. Geographical and Bathymetrical Distribution of the Family. 
Of the forty-three species described here, sixteen come from Denmark, and one of 
these was also found at le Croisic; eight are from Norway, eight from West-Greenland, and 
two of these also in the Kara Sea, three only from the Kara Sea, besides the two which 
are also found in Greenland, four from Sicily, two from the Pacific near the East-coast of 
Asia, one from the Cape, and one from the West-Indies. It may be added that in the 
most northern part of Norway and in the Barents Sea there has been found an undetermined 
species of Choniostoma, though no doubt one of those which occur in the Kara Sea, that 
one species (Spheronella Leuckartii Sal.) was taken at Naples, another species (Homoeoscelis 
sedentaria (Bonn.)) in the Atlantic off Gascogne, and besides, a non-described Spher. diadema 
G. and B. in the Mediterranean. Without counting Norway, whose species — with one 
exception — have been discovered and sent me by Prof. G.O.Sars, the number of species 
from the different countries and seas is nearly proportional to the material which our museum 
possesses of Amphipoda and Cumacea — the two orders in which most parasites have been 
found — from the same localities. From this fact we can pretty safely draw the conclusion 
that the examination of a manifold larger material than was at my disposal, e. g. from the 
Mediterranean and from eastern Asia, will bring numerous unknown forms to light. The 
above statements also suggest the probability that the family is distributed over all seas, 
though of course I cannot form any precise notion how far its geographical distribution 
will extend, when some day the chief bulk of the existing species has been discovered, for, 
as stated in the preface, I think there can be no doubt that their number amounts to 
hundreds. 
Unfortunately I am not prepared to give many data concerning the bathymetrical 
extent of my species, for in most cases I lack precise indication of the depth im which the 
special hosts have been found. Most of the sixteen Danish species and four species from 
the Mediterranean were taken in a depth of between a few and twenty-five fathoms, but 
unfortunately I cannot state precisely in how shallow water the most littoral species is 
generally found, or may sometimes be found; it may be stated, however, that a specimen 
of Bathyporeia with its parasite, Spheronella paradoxa, was taken ina depth of between eight 
and eighteen feet. Stenothocheres egregius was taken in a depth of forty fathoms, a few 
specimens in a depth of between forty and sixty fathoms; my only specimen of Spher. 
10* 
