48 THREE CRUISES OF THE “BLAKE.” 
will serve as an example. In this species the filaments of each 
antenna are greatly elongated, — fully once and a half the 
length of the body; the legs increase in length towards the 
posterior extremity, and the three anterior pairs have minute 
claws; the dactyli of the two posterior pairs, nearly twice as 
long as the preceding pair, are exceedingly weak and slen- 
der, and are evidently tactile rather than ambulatory organs, 
— modifications which seem adapted to the deep-sea life of 
these animals. We are constantly struck with the exquisite 
delicacy and great diversity of the organs of vision, of hear- 
ing, of touch, and even of smell, in the deep-water crustaceans. 
The antenne and claws are frequently of excessive length, as 
if to facilitate exploration of the ooze and the sounding of 
objects. 
We find in deep water huge schizopods, Gnathophausia (Fig. 
249), of a beautiful red color. The majority of schizopods pre- 
viously known were mainly pelagie, and belong to a group of 
small crustaceans which have the thoracic feet all alike, divided 
into two branches and sometimes carrying free gills. Some of 
these deep-water schizopods are provided with special organs 
SER of phosphorescence, such 
f \ as luminous plates behind 
the eyes or over the legs. 
Among the various groups 
of crustaceans some have 
phosphorescent eyes, while 
in others the phosphores- 
cence is diffused, or limited 
to special parts of the body 
at the time of breeding, or 
25 Y idis Yr when irritated. 
Fig. 250. — Syscenus in- Fig. 251. — Roci- Among the Atlantie spe- 
A v T RO + cies of isopods, we may fig- 
ure the bright orange Sysce- 
nus (S. infelix, Fig. 250), which is found at a depth of nearly 
400 fathoms, and Rocinela (A. oculata, Fig. 251), the upper 
surface of the head of which is nearly covered with large ocelli 
arranged in rows. From the collection made in the West Indian 
