178 
THE VOYAGE OF H.M.S. CHALLENGER. 
acutely lanceolate superior lamella, and a similar ventral lamella. The setigerous lobe is 
pointed, with -a long spine projecting considerably beyond the tip, and a tuft of long 
translucent, tapering bristles. There is nothing further to aid in diagnosis. 
Halodora, Greeff. 
Halodora reynaudii, Aud. and Ed. (?) (PI. XXXIIIa. figs. 1, 10-12, 14-18, 20-22 ; 
PI. XXXI Va. figs. 1, 3-6). 
Habitat . — Caught on the surface of the sea, near Station 3 (south of the Canaries), 
February 18, 1873 ; lat. 25° 45' N., long. 20° 14' W. ; surface temperature, 65°'0. 
The specimens of this species are so imperfect that no reliable description is attainable. 
The soft parts of the feet and cirri, as well as the bristles, are absent. The body is barred 
with reddish-brown, and is not much tapered in front. The eyes are large, and the 
cornese external. The absence of the hard processes in the proboscis points it out as 
different from Asterope, though there are two long cirriform appendages to the organ in 
front. The dense wall of the proboscis is formed of a closely arranged series of circular 
and radiating fibres, while the hypodermic lining is raised into prominent and somewhat 
thick folds. The inner surface shows so little of the cuticular element that it resembles 
the section of a lining that during life has been coated with cilia. 
The nerve-area is placed somewhat higher than usual, being situated above the level 
of the inner borders of the ventral longitudinal muscles. The thick, circular, muscular 
coat passes to its exterior, and the oblique muscles likewise pass below it in the anterior 
region of the body, the only one in a condition for examination. The nerve-cords are 
comparatively large. 
The eyes of this specimen have been studied minutely by Dr. Marcus Gunn, whose 
Eeport thereon is as follows : — 
Eye. — In general form, in the arrangement of its parts, and in the structure of its 
outer coats, the eye of this species conforms with the description given by Greeflf of the 
eyes of the Alciopidae examined by him. 
Lens . — ’The lens is globular as in the other members of the group, and its large size 
renders it easily visible to the naked eye. Its diameter is 0’32 mm. On section (antero- 
posterior) it is seen to consist of a granular, softer, cortical part surrounding a clear, 
highly refracting, dense central part. The cortex extends inwards for about one-eighth 
of the entire radius. The clear dense part immediately within the cortex is interrupted 
about midway between centre and periphery by a series of crescentic spaces arranged in 
concentric rows. The specimen figured exhibits a very finely granular material in the 
position of the centre of the nucleus (PI. XXXIIIa. fig. 22). 
