740 
THE VOYAGE OF H.M.S. CHALLENGER. 
the collection, one of which somewhat exceeds in size even the Gnathophausia 
gigas, the specimen secured being a full-grown female with enormously developed 
marsupium, and exhibiting a rather striking appearance from its thick-set form 
and very large, loosely attached carapace. This form, too, bas proved to be identical 
with a peculiar Crustacean described by Professor Dohrn as Lophogcister ingens, from a 
very incomplete specimen sent to him from the museum in Hamburg. The GnatJio- 
phausia zocea (see fig. 262 ) of Suhm, recalls in a most striking manner, by the form of 
its carapace, the larva (zooea) of the Brachyura, and seems to be the most widely distri- 
buted species, being found on both sides of the Atlantic and also in the Pacific. 
Fig. 261 — Gnathophausia gigas, Sulim. Lateral view. 
“ The remarkable form, Eucopia australis, Dana ( = Chalaraspis unguifer, Suhm), 
seems also to be widely distributed in the great depths of the oceans, but, owing to 
its remarkably soft integument and fragile limbs, most of the specimens in the collection 
are in a more or less imperfect state. 
“The subdivision Euphausiiclse, in contrast to the Lophogastridse and Eucopiidm, 
seems to consist almost exclusively of true pelagic species, some of them being often found 
in great profusion swimming about near the surface of the sea, especially at night. As 
was first stated by Vaughan Thompson, these elegant and pellucid Crustacea are highly 
Fig. 262 . — Gnathophausia zocea, Sulim. 
phosphorescent, the generic denomination, Noctiluca, given to them by that author 
being in fact derived from this peculiarity. The mode by which this phosphorescence is 
effected does not seem, however, to have been fully ascertained hitherto. It is true 
several authors have mentioned in these Crustacea a number of peculiar vivid-coloured 
globules, occurring both on the sides of the trunk and along the ventral face of the tail 
between the bases of the pleopods ; but the structure of these globules generally has 
suggested the supposition that they were accessory eyes. The re-examination of the said 
