of the Yirginimi Coast. 



255 



Between the 40th and 50th 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 setse 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 difierent individuals ; 

 middle third sometimes green. 



Segments short, numerous. 



Length usually about 70'"'", with a diameter of l""*". 

 Low water, mud and sandy mud. 



ARICIDEA n. gen. 



One antenna. Feet biramous. 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 n. sp. 



PL. IX, FIGS. 127-132. 



Head, posterior half convex, sides rounded ; anterior 

 half just in front of the single antenna suddenly depressed 



