294 CHONE FAUVELI. 
fig. 2b) are avicularian and form a single row, diminishing in size from the dorsal tothe 
ventral end adjoining the bristles. There are about thirty-six hooks in each row anteriorly. 
Moreover, the hooks at the upper end of the row have a larger base than those next the bristles, 
for in the last hooks the base is in a line with the neck and devoid of the anterior prow. In 
the upper hooks the main fang is large and sharp, the anterior outline below it deeply 
concave to the prow, after which it is nearly straight. Four distinct teeth occur above the 
main fang. The posterior outline is irregular, a slight hollow occurring at the neck, then 
a convexity, from which a straight line runs to the angle at the upper part of the base, another 
straight line joining that bounding the free end. The base and neck are boldly striated, 
the former transversely, the latter longitudinally. At the lower end of the row the posterior 
outline of the hook is nearly straight, only a sight elevation occurring in the middle, whilst 
the anterior outline of the base is prolonged downward with a slight posterior inclination, 
so that it has a base elongated in the line of the neck. In some large forms from St. Andrews 
these hooks were of a deep brown hue. 
In contrasting these with the hooks of C. infundibulifornus, the curvature is less, the 
neck shorter, and the crown somewhat flatter. Moreover, whilst the body of the arctic 
specimen is larger, the hooks are proportionally smaller. In Chone infundibuliformis 
the hook (Plate CXXIX, fig. 66) in the middle of the body considerably diverges from 
that of OC. faweli, since the base is more massive, the prow has a slight process 
projecting downward, and the gulf below the acute main fang, instead of having a nearly 
uniform outline on its inner edge, has a distinct indentation, marking off, as it were, 
the region of the prow. But the most divergent feature is the crown, which is flattened, 
and provided at its posterior edge only with five or six small teeth in lateral view—in 
. contrast with the four large teeth of the British form, which project well over the main fang, 
and the strie from which occupy a considerable portion of the neck; the striz adjoining 
(in front) are parallel to these, whereas in the arctic hook the long striz from the smaller 
teeth on the crown are indistinct, those in front being alone conspicuous. The posterior 
outline in the two hooks likewise differs, the arctic form beg evenly convex till near the 
base, where it 1s truncated, the British having this portion of the posterior edge concave. 
The distinctions noted continue posteriorly. Thus the bristles near the tip of the tail 
in the British form, while they have greatly elongated tips, retain the marked constriction of 
the shaft below the tip, and the dilatation beyond it. On the other hand, the extremely slender 
tips of C. infundibuliformis have only a trace of wings, and the slight constriction of the 
shaft below and dilatation above the commencement of the wings would not at first sight 
be noticed. The terminal hooks in the British form have a more regular posterior outline, 
but otherwise keep to the type seen in front, the main fang and the teeth above it being 
specially distinct ; on the other hand, those of Chone infundibulifornus retain all the distine- 
tive features already mentioned, the minute teeth at the back of the flattened crown being 
so indistinct as to suggest fusion. . 
When the digestive tract of C. Fawveli is exposed, it presents anteriorly prominent oral 
papillee and glandular organs on each side. The anterior region of the tract is brownish in 
colour, chitinous and very pliable, and after a short course it merges into a rounded and more 
distinctly moniliform portion, which, gradually diminishing in calibre, ends in a small anus. 
The contents of the gut showed many diatoms, fragments of the spicules of sponges, fragments 
