of the Viryinian Coast. 55 
Between the 40tli and 50tlj feet the dorsal cirri come to 
be nearly as long as the branchiae, and of the same form. 
With the transfer of the ventral rami to the dorsal surface, 
the feet and branchiae become connected by an elevated 
transverse membranous ridge. The dorsal and ventral 
setse are alike. The dorsal cirrus stands back of the bundle 
of setae which continues to arise at its base, while the ven- 
tral setae arise from the summit and anterior face of the 
ventral ramus. All the setae are very long. Throughout 
most of its length the diameter of the body is uniform. 
There is a somewhat rapid diminution in the first four 
segments; and a gradual diminution in the posterior 
fourth; the last segment having about one-half the width 
of the middle segments. The anterior segments are slightly 
concave above (f. 125), slightly convex below; posterior 
segments (f. 126) flat, or very slightly convex above, broadly 
rounded at the sides and below, with a distinct median 
ventral depression. 
Anal cirri, four, delicate, subulate, white ; the superior 
of the length of the last five segments ; the inferior, short. 
Color, red, shade varying in different individuals; 
middle third sometimes green. 
Segments short, numerous. 
Length usually about TO""', with a diameter of 1°"°. 
Low water, mud and sandy mud. 
ARICIDEA n. gen. 
One antenna. Feetbiramous. Dorsal rami with cirri; 
ventral rami with cirri on anterior segments only. Bran- 
chiae on anterior segments only. Setae all simple, capillary. 
First segment with setae, no tentacular cirri. 
ARICIDEA FRAGILIS 71. sp. 
PL. IX, FIGS. 127-132. 
Head, posterior half convex, sides rounded ; anterior 
half just in front of the single antenna suddenly depressed 
