EEPORT ON THE ANNELIDA. 
309 
bands of fibres from the alimentary canal, and the connective tissue which surrounds 
the great median blood-vessel immediately above them. No neural canal is visible. 
The oblique muscles are very slightly developed, and the contrast with the typical 
species in this respect is marked. The ventral longitudinal muscles are massive and 
elongate-ovoid in section, whereas the smaller dorsal muscles are ovoid. The alimentary 
canal is fixed to the median dorsal wall almost without a pedicle, and a considerable 
blood-vessel occurs at each side. A similar pair of vessels lie close to the wall of the 
intestine above the great ventral. The nerve-cords are much flattened, and the difference 
between them and the ganglionic enlargements is pronounced. 
The Tradopia maculata of Dr. Baird,^ from Madras, possesses bifid branchi^ 
anteriorly, but posteriorly the divisions are more numerous. A species procured by 
Mr. Whiteaves, in the Gulf of St. Lawrence, is closely allied to the present form, but 
differs in the great length of the ringed bases of the tentacles. 
A specimen dredged off Sombrero and St. Thomas, either in 460 or 390 fathoms, 
but which locality is doubtful, approaches the foregoing so closely that it has not been 
thought necessary to form a new species. It is fragmentary, measuring about 20 mm. 
in length and 2 '3 mm. in breadth. 
The head has lost its tentacula, their basal-regions, which seem to be large, alone 
remaining. The tentacular cirri are filiform and of considerable length. The frontal 
lobes are elongate and ovate. The general asj)ect of the maxillae agrees with Nothria 
tenuisetis, but the posterior appendages have a straight instead of a convex outer edge, 
the latter indeed, being parallel to the line bounding the inner triangles, and the centres 
are somewhat more tumid. The pigment is thus in the form of a straight band on each 
side. The left great dental plate has eight teeth, the right nine. The left paired 
plate possesses five teeth, and the accessory (as on the right) has a tooth. The left 
unpaired shows about nine, and the right lateral seven teeth. The same blackish 
pigment is present on both sides, in the alveolus of this and the corresponding plate on 
the left, as in the previous examples. The mandibles also agree with those in the 
latter in regard to the black lines on each side of the fissure, and in the irregular denti- 
culations along the anterior (cutting) margin. 
A slight divergence occurs in the origin of the branchiae, which appear on the 
seventh foot instead of the ninth ; moreover, the bifid condition continues somewhat 
further backward. The organs are also shorter, but the condition of the specimen is 
unsatisfactory, and therefore such characters are unreliable. 
In transverse section this corresponds with the foregoing in the general shape of the 
body, and in the proportions of the dorsal and ventral longitudinal muscles. The 
vertical muscles passing by the side of the alimentary canal are, however, much stronger, 
for considerable bands pass to the hypoderm on each side of the nerve-area. A large 
1 Proc. Linn. Soc. Land., vol. x. p. 355. 
