394 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
10. Harmothoe tuta (Grube). PI. 2, figs. 18, 19. PI. 3, figs. 
*20 ^9 
L* \J — — —j . 
Polynoe tuta Grube. Arch. f. naturgesch., jahrg. 21, bd. 1, 1855, 
p. 82. 
Halosydna tuta Baird. Journ. Linn. soc. London, vol. 8 (Zool- 
ogy), 1865, p. 188. 
Form elongated, of nearly uniform width throughout anterior 
two thirds, gradually tapering in posterior third to extremity; 
somites numerous and variable in number (77-83) ; elytra not all 
paired, 35-38 on each side; borne on somites 2, 4, 5, 7 ... . 23, 26, 
29, 32 ....; general color of formalin specimens, very pale brown; 
a transverse band of darker brown on every somite of anterior 
half, and a median dark stripe. 
Prostomium (Fig. 18) distinctly bilobed, median furrow extend¬ 
ing to its base ; lobes rounded anteriorly, widely sundered by the 
thick napiform basal joint of tentacle ; eyes placed well forward, 
medium-sized, black; the anterior pair laterally, the posterior pair 
upwardly, directed. Basal joints of antennae inserted below the 
basal joint of tentacle, on underside of prostomium; distal segments 
of antennae and tentacle very short, nearly equal, not exceeding 
length of prostomium. Palpi also short, rapidly tapered to subulate 
tips ; constricted at intervals in contraction ; all cephalic appendages, 
like tentacular and dorsal cirri, sparsely beset with minute papillae. 
Tentacular cirri considerably longer and more slender than ten¬ 
tacle ; subterminal enlargement very slight. 
Elytra slightly variable in shape, nearly orbicular (Fig. 20), 
some broadly reniform, strongly imbricated, meeting across median 
line; with very few microscopic tubercles, thin and translucent, suf¬ 
fused with smoky brown. 
Parapodia (Figs. 18, 19) elongate, nearly or quite equal to 
width of dorsum between elytrophores; dorsal setae rather numer¬ 
ous, much shorter and more slender than the ventral (Fig. 19), 
divaricate, slightly curved, rather coarsely serrated along convex 
border near tip (Fig. 21). Ventral setae numerous (over twenty), 
with about twelve “ frills ” near the slightly expanded tip. Point 
nearly straight, acute. Dorsal ramus short for this genus, with de¬ 
cided finger-like process, to tip of which the acicula extends. Ven¬ 
tral ramus stout, fleshy, with thick, stumpy, fingerdike process which 
does not receive tip of acicula. Ventral cirrus short, abruptly taper¬ 
ing to a fine point. 
