362 
THE VOYAGE OF H.M.S. CHALLENGEE. 
The segments resemble those of the common Ephesia g^'acilis. Dorsally is the 
large globular appendage, which exhibits a much more minute papilla than in the latter 
form. Internally the globular processes have the elongated granular structures. The skin 
of the foot is likewise covered with many papillae. A single spine supports the foot, the 
bristles in which differ from those of Ephesia gracilis in having the terminal piece less 
hooked as well as distinctly differentiated from the end of the shaft (PI. XXTTa. figs. 22, 
23). The terminal piece forms a somewhat conical process with an oblique base, the 
dorsal margin being slightly convex, the ventral slightly concave. The shaft is somewhat 
curved, and is dilated at the tip below the bevelled articular surface. The bristles are 
very translucent, and approach those of Ephesia canadensis, a species, however, which 
differs in other respects from this form. 
Ephesia antarctica is a very large example of the genus, and yet it inhabits 
uncongenial waters. 
The muscular intestine contains a central whitish mass of minute Diatoms and other 
organisms composing the ooze. The muscularity and elasticity of the alimentary canal 
are remarkable. 
The cuticle in this form is tough and hyaline, but the hypoderm and the circular 
muscular coat are feebly developed. The longitudinal muscles have about the same 
proportional thickness as in Ephesia gracilis. The ventral longitudinal muscles are 
divided into two distinct regions by oblique fibres which pierce them in a direction from 
above inward and downward. In the intergangiionic regions the oblique muscular fibres 
form a well-marked cross beneath the isolated nerve-cords, which are nearly round, with 
a central granular area and a pale firm investment. Towards the anterior third the 
proboscis fills up the entire space within the body-wall. Externally (in retraction) is a 
dense longitudinal coat, the fasciculi of which are somewhat radiate. A thick circular 
layer, the fibres of which are interwoven, follows on the inner side, then a slightly 
developed hypoderm, and internally a dense cuticular layer elevated into many promi- 
nent frills, each having a central axis of hypoderm. 
Family Chloka:mida;. 
The distribution of this family is in some respects noteworthy, both as regards area 
and depth. Thus most of the specimens described by former voyagers come from shallow 
water or between tide-marks, but the explorations of the Challenger have carried these 
peculiar forms to a depth of 2500 fathoms, or nearly twice the depth at which the 
naturalists on board the “ Porcupine ” had found Trophonia glauca, Malmgren. More- 
over, the wide distribution of the remarkable intermediate type, Bushiella abyssorum, is 
interesting in connection with the view that the ancient forms have been gradually driven 
into the great depths by the more recent types attaining supremacy in the shallower water. 
