444 
THE VOYAGE OF H.M.S. CHALLENGER. 
ventral lobe, a large lamellar process in front of and beneath the first branchia, a 
conspicuous fan-shaped lobe under the second, and lastly, an elevated fold running from 
the root of the third branchia downward. The latter is diagnostic when compared with 
Amphitrite cirrata. The long branchiae spring from three short, graduated trunks on 
each side, the posterior being the longest. 
A prominent papilla occurs below each setigerous tubercle in the first six segments, 
and a similar process below the second branchia. The ventral surface of the somites 
bearing the first and second branchiae presents somewhat undefined glandular scutes, that 
bearing the third branchia has a distinct though narrow scute, while the ten following 
bear fully formed scutes. 
The muddy contents of the intestine showed numerous Diatoms, sponge-spicules, 
fragments of minute Crustacea, minute ova, and many sand-grains. Some from Royal 
Sound again, besides the latter Diatoms and sponge-spicules, presented peculiar pointed 
conical bodies like Radiolarians, and fragments of Polyzoa. 
In section the nerve-cords occupy the typical position, viz., external to the circular 
muscular coat, and are therefore hypodermic. They are somewhat ovoid in shape, and 
have a fibrous external boundary. A minute neural canal lies in the middle line 
superiorly between the cords. The strong oblicpie muscles are inserted on each side at 
the external boundary of the area. A thin stratum of longitudinal fibres occurs above 
the circular coat in the somewhat wide interval between the longitudinal ventral muscles. 
The wall of the alimentary canal appears to be less rigid than in the Ampharetidae, though 
the structure is similar. 
Grube’s Amphiti'ite vigintipes ^ has hooks somewhat similar in shape, but there are 
from twenty to twenty-two bristle-bundles. It occurs in the Red Sea, and ranges, 
according to Marenzeller,^ to Japan. 
Terebella, Linnaeus. 
Terebella crassicornis, Schmarda '? (PI. XXVIIa. fig. 19). 
Terebella crassicornis, Schmarda, Neue wirbell. Thiere, I. ii. p. 43, figs, a, b, and c, 1861. 
Habitat. — A fragment of the posterior region of a large Terebella from the tidal 
region, Bermuda, June 1873. The longest piece measures 70 mm., and the greatest 
diameter is 6 mm. 
The hook-bearing pinnae present the ordinary structure. The uncini (PI. XXVIIa. 
fig. 19), which are the only organs of much diagnostic value in the softened specimen, 
approach those figured by Schmarda from Jamaica [Terebella crassicornis), and have a 
1 Anneliden des rothen Meeres, op. cit., p. 29 (sep. Ahd.). ^ Siidjapan. Annel., op cit., p. 199, Taf. i. fig. 1. 
