846 
THE VOYAGE OF H.M.S. CHALLENGER. 
but it is by no means certain that these specimens came from the bottom. It was 
frequently noticed that some of the Copepods in the tow-nets sent down to great 
depths were of a bright red colour, similar to the Shrimps brought 
up in the trawlings in deep water. 
Remarkably few fish-parasites were brought home by the 
Expedition. One of the most remarkable of these is Lerncea 
abyssicola, an undoubted deep-sea form, seeing that it was attached 
to a specimen of the curious abyssal Lophioid genus Cercitias. 
The peculiarity in which it differs from all other parasitic Copepoda 
is its transparency, its colour during life being of a reddish brown. 
It is represented in fig. 314. 
Altogether one hundred and six species have been enumerated 
in the Report, forty-three of which are new, and for their reception 
thirteen new genera have been constituted. This number is 
inconsiderable relatively to the large number of genera and species 
previously known, but nevertheless the collection has enabled 
Dr. Brady to make valuable additions to the knowledge of this 
group. 
The Ostracoda . — The Ostracoda are small laterally compressed 
Crustaceans whose bodies are completely enclosed in a bivalve 
shell. They exist, although in very limited numbers, in the most 
profound depths of the sea, and the number of abyssal genera and 
species has been greatly increased by the Challenger Expedition. 
In those large abyssal areas where, as commonly happens, 
the ocean-bed consists of pure Gflobigerina ooze or of red clay, one 
usually finds a small number of Ostracoda ; the specimens con- 
sisting of detached valves, frequently much worn and broken, 
or, more rarely, of perfect though empty shells. These shells 
evidently belong to animals which lived at the depths where 
they were found. 
A peculiar interest attaches to the Ostracoda from the fact that they alone of all 
the higher Microzoa are found in fossil strata in sufficient numbers to afford grounds 
for an exact comparison between the fauna of the present and those of bygone geological 
epochs. However, as a whole, the results of the Challenger’s work in this department 
are not very important or novel. Very few new and remarkable variations of 
structural type were found. The Ostracode shells of the present age present different 
features according as they are found in salt, estuarine, or fresh water, so that the 
specialist in coming upon a geological stratum containing these shells can at once 
Fig. 314.— Lerncea abyssicola, G. 
S. Brady, parasitic on Cera- 
tias (from a drawing by the 
late R. v. Willemoes Suhm). 
oe, oesophagus ; st, stomach ; 
i, intestine ; m, muscular por- 
tion of intestine ; ov, ovary ; 
v, vulva ; a, anus ; os, ovisac. 
