MYXICOLA. 309 
as is also the great size of the vessels generally (Fig. 162). In this region a chloragogenous 
mass envelops the vessel above the nerve-cord, and in transverse section forms a compact, 
brownish, bilobed mass with the vessel in the centre (lig. 163). 
The contraction of the powerful longitudinal muscles, especially posteriorly, causes the 
soft hypoderm to assume regular wrinkles (Fig. 164), as well as throws, with the aid of the 
nc 
Fic. 163.—The nerve area of Myzicola infundibulum, more highly magnified. c., neural canals; vv., large 
ventral blood-vessel. 
septa, the alimentary canal into deep folds. In this section the massive muscles of the 
body-wall are clearly shown. On the whole the muscular investment anteriorly is more 
massive than in Sabella, and the finely pennate condition is a special feature. 
Claparéde, Meyer and De St. Joseph have more or less gone into details of the structure 
of the body-wall, the muscular, digestive, circulatory and nervous systems. De St. Joseph 
(1898) treats of the secretion of the tube, excretory organs, muscles and _nerve-cord. 
Claparéde in the generic characters states that uncini are absent in the anterior region of 
Fic. 164.—Longitudinal section of the caudal region of Mywicola infundibulum. 
the body—probably a printer’s error. Numerous interesting observations on the structure - 
of this species were made by this author (1873). He describes the glands as distributed 
generally throughout the hypoderm for the abundant secretion of mucus. The segmental 
organs (only a pair) are much folded and pigmented as well as highly vascular. He did not 
connect these with the issue of the reproductive elements, which he thought were discharged 
at a pigmented (violet) spot above each torus. Myzxicola, he states, is exceptional in having 
the longitudinal muscular layer of the gut internal—next the epithelial coat, the reverse 
of the usual condition in the Polycheta. The same condition was found by Claparéde 
in Spirographis Spallanzani. He also thought this arrangement occurred in Cheetopterids 
