288 CHONE. 
that no mesentery is apparent. The ventral longitudinal muscles likewise form two areas, 
the base of each being central, the apex on either side. The inner edge of each muscle is 
separated by a considerable gap in which the nerve-cords lie. Hach has a small neural canal. 
At half-an-inch in front of the tip of the tail no evident dorsal notch occurs in the hypoderm, 
but a deep median groove exists ventrally—Fig. 161. The circular muscular coat is still con- 
spicuous. Each moiety of the dorsal longitudinal muscle is now separate, the outer being 
Fre. 160.—Transverse section of the body-wall of Chone Fauveli about half an inch from the front. 
The outlines indicate the complex volutions of the muscular fasciculi. Letters as before. 
Fic. 161.—Transverse section of Chone Fawveli half an inch in front of the tip of the tail. 
the larger, and between it and the inner a strong vertical band of muscular fibres leaves 
the dorsum, joins the oblique, and passes to the outer side of the nerve-trunks, in each of 
which a small neural canal exists at the upper part, the nerve tissue completely surrounding it. 
The representatives of the genus Chone in northern waters seem to be in a somewhat 
confused condition, since the young of certain forms have been described as different species. 
At least five species, however, are clearly defined, viz., the characteristic Chone infundabuli- 
formis, Kroyer, of the Arctic Seas, which appears to be rare in most collections, but was pro- 
cured by the “ Valorous ” in 1875. This form has often been confounded with another species, 
