REPORT ON THE ANNELIDA. 
351 
Posteriorly the terminal pieces of the dorsal bristles are more evidently spinous. In 
the lower ventral series, again, the great increase in size of the shafts and their articular 
processes, and the shortening of the terminal pieces, are most noteworthy. About the 
ninetieth foot there are generally three in the inferior ventral series, one of which is 
represented in PI. XXIIa. fig. 15. The sabre-shaped upper ventral bristles are little 
altered either in form or size, and much resemble that shown in fig. 14. 
In this form the cuticle is' thin, but the hypoderm is more decidedly developed than 
usual, and it is further the seat of the l)rownish-red pigment. The circular muscular 
coat is thinner, but its disposition is similar. The dorsal longitudinal muscles are 
separated by the attachment of a strong band of median fibres. The nerve-area shows 
certain peculiarities ; thus when the section is made through a ganglion (PI. XXX Va. 
fig. 6), the area is broad above and narrow below, the two neural canals being situated 
near the upper border. Internally (superiorly) the area is invested on each side by a 
large muscular mass formed by a difierentiation of the inner region of the ventral 
longitudinal muscle, which also shows the division formerly mentioned. When, how- 
ever, the section is made in the anterior third of the body between the ganglia 
(PL XXXVa. fig. 7), it is found that the cords are separated by a strong band 
of muscular fibres, apparently connected with the alimentary canal, which pass between 
them to the hypoderm. Each nerve-cord is somewhat ovoid, and has a neural canal at 
its upper and inner border.^ The reproductive elements (ova) appear at the outer 
borders of the ventral longitudinal muscles at the bases of the feet. The hypodermic 
region of the proboscis is tinted of the same reddish-brown hue as that of the 
body-wall. 
Those authors (De Quatrefages, Kinberg, Ehlers, and Grube) who have examined 
Hemipodus agree in stating that there is only one bundle of jointed bristles, but the two 
groups are clearly shown in every foot of the present form, and it is possible that in some 
cases the smaller upper bundle has been overlooked. Moreover, whilst anteriorly a 
single spine exists, two are conspicuous posteriorly. 
The description of Kinberg’s Hemipodus patagonicus, from York Bay, Strait of 
Magellan,^ is so indefinite that identification is uncertain, though both have the buccal 
segment dilated posteriorly. No branchiae occur in the present form. Both Ehlers® and 
Grube ^ allude to the distinctive characters and distribution of Schmarda’s species from 
the west coast of South America. The genus Hemipodus of De Quatrefages® and these 
authors, indeed, is confined to the region mentioned. 
^ Prof. E. Eay Laukester {Ann. and Mag. Nat. Hist., ser. 4, vol. xi. p. 92, 1873) is of opinion that the arrangement 
of the nerve-cords and their sheath with the supporting muscles in Glycera offers certain relations to the vertehrate 
notochord. Many Annelids resemble Glycera in the disposition of the nerve-cords. 
2 Ofversigt k. Vetensk.-Akad. Fdrhandl., Arg. 22, No. 4, p. 245. 
^ Borstenwurmer, Ed. ii. p. 645. Op. cit. 
5 Anneles, t. ii. p. 194. 
