196 
THE VOYAGE OF H.M.S. CHALLENGER. 
organ on the ventral surface (PL XXX. fig. 6). The density of the pharyngeal wall is 
noteworthy. The buccal segment bears the usual pair of cirri on each side. 
The complete anterior foot (PL XXXIIL fig. 6) has dorsally a very long, slender, 
moniliform cirrus of about thirty-three segments. The organ tapers from the short basal 
division to the apex. The setigerous region is bluntly conical, and bears a few stout 
bristles (PL XVa. fig. 16 ), the shafts having dilated ends of the type common amongst 
the Syllidae, but no example possesses a terminal appendage; indeed, from the “finished” 
state of the tips of the shafts such would seem to have been their ordinary condition. 
The ventral cirrus has the form of a slender tongue-shaped process, the tip extending 
decidedly beyond that of the setigerous region. 
Posteriorly the dorsal cirri become more slender, and the ventral somewhat shorter, 
so that they do not quite reach the tip of the setigerous region. The bristles are fewer 
than in front, only one or two being, as a rule, present. They are stout, and have the 
tips curiously modified (PL XVa. fig. 17), like those of Syllis gracilis of the Channel 
Islands. The tip of the shaft is minutely bifid, this modification affecting the part 
which forms the. articular edge in other bristles of the same nature. 
As indicated by the bristles, this form approaches the group containing Syllis gracilis, 
Grube, but is especially allied to Syllis spongicola, Grube,^ a species not uncommon in 
the Mediterranean, and also at Madeira. The cirri in the present species seem to be 
considerably longer, and the structure of the bristles is diagnostic. It is interesting to 
note that in some forms, as in Grube’s Syllis vancaurica,^ and in Eusyllis, Malmgren, the 
posterior bristles deviate considerably from the anterior. These differences are well shown 
by Marenzeller in Eusyllis assimilis.^ 
Syllis brasiliensis, n. sp. (PL XXX. fig. 7 ; PL XXXIIL fig. 7 ; PL XVa. fig. 20). 
Habitat. — Dredged at Station 122 (off Barra Grande, Brazil), September 10, 1873; 
lat. 9° 5' S. to 9° 10' S., long. 34° 50' W.; depth, 350 fathoms; surface temperature, 
77°'5 ; sea-bottom, red mud. 
A form about the size of the last-mentioned species, and also furnished with a large 
proventriculus, which gives a rasp-like appearance (from the transparency of the integu- 
mentary tissues) to the region occupied by it. The dorsum is prominent and much 
arched, the ventral region marked by a groove. 
The head (PL XXX. fig. 7) possesses a similar form to that in Syllis setubalensis, i.e., 
has a short antero-posterior and a long transverse diameter. The four very distinct 
blackish eyes are similarly arranged. The tentacle springs from the middle of the head 
1 Archivf. Naturgesch., 1855, p. 104. ^ Annel. NoYara-ExpecL, p. 25, Tab. iii. fig. 2, c. 
3 Zur Kenntniss d. adriatischen Aniu-b, p. 30, Taf. iii. fig. 2, B. 
