110 STALK-EYED CRUSTACEA. 
free throughout its length, whereas in Polycheles this process is short and 
curved, with the distal end flattened in such a fashion as to form a facet 
which slides over the lower face of the basal segment of the antennules. 
The huge spherical carapace of Eryonicus perhaps serves as a hydrostatic 
apparatus, by means of which the animal is enabled to lead a free-swimming 
life at some distance above the ocean bottom, The great depths of the sound- 
ings at some of the stations where Lryonicus has come up in the trawl may 
be delusive, as in the case of swimming Hoplophoride and Sergestide, which are 
often found in the trawl that has been lowered to great depths. At Station 
3888, twenty-five miles from the nearest land, where the depth was 1168 
fathoms, the Tanner self-closing net* was lowered to 400 fathoms and towed 
for seventeen minutes. The net was then hauled up to the surface after the 
lower part had been securely closed by the messenger at 400 fathoms. The 
lower part of the net was found to contain absolutely no life, while the upper 
part, which had remained open all the way from 400 fathoms to the surface, 
contained four specimens of Lryonicus, 19-29 mm. long, together with other 
swimming forms.f At Stations 3375 and 3385, although captured in the 
trawl which had been lowered to the depths of 1201 and 1832 fathoms, 
Eryonicus was found associated with several swimming forms. At Station 
3403 a specimen of Lryonicus spinulosus was brought up in the trawl where 
the bottom was only 584 fathoms. 
From these facts it is possible, if not probable, that Hvyonicus leads a free- 
swimming existence at depths moderate compared with those frequented by 
truly abyssal species. On the other hand, the structure of its visual organs 
and its absence from collections made with the surface tow-net preclude the 
thought of its living at or very near the surface. 
Eryonicus ce#cus Barr? 
Plate B., Fig. 2; Plate XXIX., Fig. 2-2 ; Plate XXX. 
? Eryoneicus cecus Bate, Ann. Mag. Nat. Hist., 5th Ser, X. 457, 1882; Rep. Challenger Macrura, pp. 122- 
126, Fig. 30, Plate XII. E, 1888. 
Eryonicus cecus ? Fax., Bull. Mus. Comp. Zool. XXTV. 197, 1893. 
Male.—The rostrum consists of a pair of very small spinules. The median 
ridge of the carapace is armed with small spines arranged thus: 2 (rostral). 
1. 2. 1. 1— 2.2.1.2. There are four minute spinules on each side of the 
* For a description of the Tanner net, see A. Agassiz, Bull. Mus. Comp. Zodl., XXIII. 46-48, 1892. 
+ See A. Agassiz, Bull. Mus. Comp. Zo6l., XXIII. 48, 49, 1892. 
