REPORT ON THE ANNELIDA. 
325 
dorsal cirrus, and being nearly as long as the latter at the twentieth foot.- The two sets 
of bristles are by and by separated by a more decided interval, in which are several 
strong spines with curved blunt tips, some having a secondary distal process, thus fore- 
shadowing the bifid hooks of the succeeding region. The delicate brush-shaped bristles 
(PI. XXVIa. fig. 3) are also present, and as a rule the dilated region at the tip is 
oblique. The obliquity would not seem to result from, position, since no other condition 
is observable. The upper fringes in all the specimens, moreover, are longer and more 
slender than the lower. 
The thirtieth foot shows a branchial process of two divisions, and the dorsal cirrus is 
very attenuate. Both organs are supported by a common base, which apparently 
divides to form them. The setigerous lobe bears the winged dorsal bristles, and 
the brush-shaped forms, but the ventral are not visible, their places being supplied by 
the large hooked spines. At the fortieth foot the branchia has four lateral branches, and 
it is thicker at the base than the dorsal cirrus. The bifid winged hooks project beyond 
the setigerous process interiorly ; and the posterior lamella has now diminished to a 
papilla, which appears just below the dorsal bristles. The dorsal cirrus now appears as 
an appendage of the considerably larger branchia. 
At the fiftieth foot (PI. XLI. fig. 9) the dorsal cirrus can hardly be differentiated 
externally from the branchial organ, though the presence of the long delicate internal 
bristles, which seem to pass almost to the tip, is diagnostic of the cirrus, and the finely 
pinnate blood-channels of the branchia. The foregoing and the posterior feet have 
three stout spines with somewhat pointed tips, besides the bifid hooks, which are much 
shorter than the former. 
Two long winged hooks (PI. XXVIa. fig. 4) now project clearly beyond the setiger- 
ous process, and the posterior lamella is invisible. The hooks show a short dorsal and a 
longer (main) ventral process, and the wing or guard at the tip is truncate, as if from 
friction. The sixtieth and seventieth feet are similar to the foregoing, each branchia 
having five or six divisions, while the dorsal cirrus is attached like an appendage to the 
base. The presence of the long simple bristles in the latter may be of some service in 
preventing the too ready collapse of the branchise in the tube. The branchiae are con- 
siderably longer than the cirri. The setigerous region of the foot is much less prominent, 
and the distinction between it and the scute beneath obscure. 
The branchiae throughout are the seat of a commensalistic Loxosoma (PI. XLI. 
figs, 9, 10), and some of them show a distinct elevation at the point of attachment of the 
Polyzoon. A few specimens of the Loxosoma also occur on the dorsal cirri and feet, 
but the majority are situated on, the respiratory organs proper. 
The intestinal pellets are for the most part composed of tightly rolled whitish fibrous 
tissue, with here and there a few sand-grains, sponge-spicules, and other debris. 
The tube (PI. XLI. fig. 4) produced by this species is one of the most remarkable. 
