42 
THE VOYAGE OF H.M.S. CHALLENGES. 
tlie sixth, a dorsal cirrus; the seventh, long dorsal bristles; the eighth, a cirrus; the ninth, 
abundantly barbed long dorsal bristles, with a few simple ones ; and so on to the twenty- 
eighth, which has a cirrus ; the twenty -ninth, a cirrus ; the thirtieth, dorsal bristles ; the 
thirty -first and thirty-second, dorsal cirri ; the thirty-third, bristles ; the thirty-fourth 
and thirty-fifth, cirri ; the thirty-sixth, bristles ; the thirty-seventh and thirty-eighth, 
cirri ; the thirty-ninth, modified small bristles ; the fortieth and forty-first, cirri ; and the 
forty-second, bristles. 
Thus the general arrangement in regard to the structure of the feet throughout the 
chief jDart of the body, viz., from the fifth to the twenty-eighth foot, is that the segments 
bear cirri and long dorsal bristles or spines (with scales) alternately, the former having 
the chief bristle-tufts directed laterally, the latter dorsally. A typical spine-bearing 
segment, e.g., the nineteenth, bears dorsally a series of boldly curved dull golden bristles 
which sweep backward and inward over its own and the succeeding scale. These bristles 
are rather broad and flattened inferiorly, but taper to attenuate simple extremities, the 
greater part of the latter region being minutely nodulated. They seem to attain 
their greatest development in those species devoid of a dorsal felt, and thus probably 
subserve a protective function.. The next inferior group consists of a tuft of lustrous brown 
spines {setce glocliidece), about three-quarters of an inch in length, which slant backward in a 
conspicuous manner (PI. IVa. fig. 5- — representing an example in which the sheath at the 
tip has been removed). A characteristic feature when contrasted with LcBtmonice JUicornis 
is the opposite or nearly opposite position of the fangs, some showing them very slightly 
alternate at the. base. There are usually five pairs of these recurved fangs, though a few 
show six, the first and last being smaller than the others. This formidable defensive 
apparatus is sheathed in two chitinous flaps (PI. IVa. fig. 6 — from the ninth foot, and 
somewhat broader than usually seen). As mentioned, a few in the ordinary feet show 
alternate fangs (PL IVa. fig. 7); and one or two equally powerful bristles of the same 
length, but with smooth tips, also^occur. Below the foregoing is a tuft of simple bristles 
having striated shafts and very attenuate tips. With the latter exception the whole of the 
bristles are advanced upward, so that they alternate with neighbouring feet. In young 
specimens the strong spines on the dorsum are often simple at the tip, and the dorsal dull 
golden simple bristles stand nearly erect instead of curving over the scales as in the adult. 
The number and variety of parasitic growths and adherent debris on these and other 
bristles are remarkable, and indicate the rich nature of the ground on which they feed. 
The ventral bristles (PI. IVa. fig. 8) have lustrous brown shafts, and project far 
beyond the feet on each side. The shaft has a long and curved hook at its distal end, 
then after an interval this is followed by a series of chitinous processes (arranged in a 
pectinate manner), which gradually diminish in size to the slightly hooked tip. Posteriorly, 
the bare part at the tip again lengthens as observed anteriorly (PI. IVa. fig. 3), and the 
spines diminish in length. There is thus a transition anteriorly and posteriorly. The central 
