282 EUCHONE RUBROCINCTA. 
the dorsal loop presents a hiatus at its ventral edge. Both dorsal and ventral longitudinal 
muscles are proportionally thicker and the body-wall more compact—Fig. 158. The aspect 
of each muscle wholly alters about an eighth of an inch from the tip of the tail. Hach dorsal 
muscle in section shows a continuous thick arch superiorly, the inner end bending downward 
and forming a coil of a turn and a half, whilst the outer and thicker end does the same. Hach 
ventral muscle, on the other hand, makes a single coil of one turn and a half from its outer 
end, and thus forms a contrast with the double coil in each dorsal. Special functions would 
thus appear to be provided for in the caudal region of this form. 
Fie. 158. Fie. 159. 
Ae il hi > 
CY AW, AAI 
La ae Se ge 
Z FS 
py 
< HUN ll 
mt 
Hi 
ii 
Fie. 158.—Transverse section of Euchone analis about + of an inch from the tip of the tail. x 30. 
Fic. 159.—Transverse section of Huchone analis about 3th of an inch from the tip of the tail. br., 
bristles; cm., circular muscle; d, intestine; dm., dorsal muscle with its coils; vm., ventral 
muscle with its large coil; ne., nerve-cords with neural canals. 
1. EuCHONE RUBROCINCTA, Sars, 1862. Plate CXXXI, figs. 2—2a—bristles and hook ; 
Plate CX XXVIII, figs. 9 and 9a—posterior hooks. 
Specific Characters.—Collar curved as it approaches the median dorsal fissure ; ventrally 
there is only a spout-like median fold. Branchiee fifteen to sixteen on each side, webbed for 
half their length. Filaments with numerous pine to the base of the slender fihform 
extremity. Narrow hypodermic wing from base of slender tip along a portion of filament. 
Tentacles two, somewhat lgulate ; tentacular cirri six to seven, thread-like. Body about 
3tinch in length, of thirty-two or more segments, nine to eleven being included in the anal 
funnel, which has a furrowed process in front and a crenulated margin. Segments two- 
ringed, with a dorsal furrow which extends in the preparations to the posterior end. 
The anterior part of the groove passes to the ventral surface between the eighth and 
ninth segments, and is contmued to the anal funnel. Anterior bristles of two kinds, the 
shorter ventral with comparatively narrow wings and curved shorter tips, the longer dorsal 
with tapered winged tips. The posterior bristles have long hair-like tips and narrow 
wings. Anterior hooks large, with long boldly curved shafts, narrowed above the 
shoulder. A main fang which comes off nearly at a right angle, and a flat crown with 
eight to nine teeth. Posterior hooks avicular, the terminal (caudal) forms having a much 
higher crown and more numerous teeth than those in front of the same region (usually five 
