320 REPORT OF COMMISSIONER OF FISH AND FISHERIES, [614] 
posterior fold. Tentacles very numerous, crowded, long, and slender. 
Branchiz four, rather small; those of the anterior pair somewhat the 
larger; those of both pairs are repeatedly dichotomously divided from 
close to the base. The divisions are short and not very numerous, and 
diverge at a wide angle. Fifteen segments bear small fascicles of slender 
sete, commencing at the next behind the last branchiferous segment. 
The third and fourth setigerous segments of the male bear small, slender 
lateral cirri. Ventral shields about thirteen ; the first six transversely 
oblong, and nearly equal in width; the last seven narrowing rapidly 
to the last, which is acutely triangular. Color, when living, light red, 
or flesh-color. 
Length, 35™"; diameter, 5"™ to 4™™. 
New Haven to Vineyard Sound, from low-water to 6 fathoms; off 
Watch Hill, 4 to 6 fathoms, in tubes composed of bits of shells and grains 
of sand, attached to Laminaria. 
Scronopsis Verrill, gen. nov. 
Body composed of numerous segments, of which 17, following the 
third, bear fascicles of slender sete, and the following ones have only 
small uncigerous lobes ; second and third segments bear branchie, 
and have their anterior margins prolonged into membranous, collar-like 
expansions; that of the second forming broad, lateral lobes behind the 
tentacles; that of the third forming behind the branchiz a dorsal col- 
lar or sheath, beneath which they can be retracted. Branchiz typically 
four. Those of the first pair usually larger, but generally one or more 
are absent, and frequently the anterior ones are smallest, or those of the 
same pair may be unequal, owing probably to the facility with which 
they may break off and be reproduced ; they are palmately branched 
and supported on elongated pedicels. Tentacles numerous and crowded. 
This genus is allied more closely to Pista than to any other yet de- 
scribed, but differs in the structure of the branchice and character of 
the collar formed by the third segment. 
SCIONOPSIS PALMATA Verrill, sp. nov. (p. 321.) 
Body elongated ; rather slender; thickened but not distinctly swollen 
anteriorly, tapering gradually to the posterior end. The setigerous feet 
commence at the fourth segment, or next behind the branchial collar, 
and are all quite prominent, the first three or four being a little smaller 
than the rest; the sete are rather long. The uncigerous feet commence 
on the second setigerous segment. Behind the last setigerous segment 
the uncigerous feet are smaller, somewhat prominent, and extend to the 
analsegment. Ventral shields about 20; the mostanterior ones are trans- 
versely oblong; the succeeding ones squarish, gradually tapering to the 
last, which are very narrow. Anal segment tapering; its orifice with 
acrenulated margin. Branchiz large, with numerous palmate divisions 
