REPOET ON THE ANNELIDA. 
389 
In transverse section this species is characterised by the conspicuously dense cuticle 
and the well-developed hypoderm. The nerve-cords are large and connate, forming a 
somewhat elliptical area in the ventral indentation of the thick circular muscular coat. 
The median neural canal is best seen superiorly in the ganglionic region. In 
the anterior third of the body the longitudinal coat is symmetrically arranged in eight 
divisions, each tightly bound internally by the translucent sarcolemma. On each side is 
a great ventral mass, above which is another about half the bulk, followed dorsally by a 
much smaller division and then a larger median one. If the strong band passing from 
the second interval [i.e., between the second and third muscles from the dorsal middle 
line) to the ventral border on each side of the nerve-area represents the oblique muscle, 
then each great inferior division is homologous with the longitudinal ventral of other 
forms. The position of the nerve-cords, moreover, at once differentiates this species from 
such types as Notomastus, in which the cords are wholly within the muscular layers. 
This form, indeed, connects Cirratulus and Clicetozone with the Halelminthidse. 
Notomastus, Sars. 
Notomastus agassizii,^ n. sp. (PI. XLVI. fig. 3 ; PI. XXI Va. fig. 15). 
Habitat . — Dredged at Station 47 (off the coast of New York), May 7, 1873 ; 
lat. 41° 14' N., long. 65° 45' W.; depth, 1340 fathoms; surface temperature, 42°'0 ; 
sea-bottom, blue mud. 
A fragment of the anterior region of a form apparently identical was brought up with 
the sounding-line off San Antonio, Cape Verde Islands. The specimen is small, and 
has been dried. 
In common with many Euroj^ean examples, the specimens consist only of the anterior 
bristle-bearing region and a portion of the succeeding. The length of such fragments is 
therefore of little moment, but it may be mentioned that the largest has a diameter of 
6 mm. at its widest part. 
In external appearance (PI. XLVI. fig. 3) this form very closely resembles the 
common British species {Capitella capitata). The snout, perha23s, is a little more acute, 
and there is no trace of pigment-s|)ecks. The buccal and the anterior regions ajDpear to 
correspond in the Same way, the latter having eleven series of bristle-bundles, each 
segment being marked by a median furrow;, which runs quite round in the line of the 
bristle-tufts. The surface presents the usual tessellated aspect. 
The bristles agree with those in the British S 2 >ecies, and no aj^jDreciable difference can 
be detected in regard to the hooks (PI. XXIVa. fig. 15). The minute denticulations in 
the crown of the latter are feebly developed, indeed, they are hardly distinguishable. A 
1 Named after Alexander Agassiz. 
