426 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
posterior end. Total number of somites, 63-90; in thorax, 20, of 
which 17 (4th to the 20th inclusive) are setigerous. Uncini begin 
at 5th somite and extend to the penultimate. Uncini uniserial 
anterior to the 11th somite, and posterior to the 20th; biserial on 
thoracic somites 11-20 (Fig. 167). 
Prostomium with dorsal ridge and small lateral lobes formed by 
its continuation to the sides; no eves. Peristomium bearing a 
semicircle of tentacles, rather thick in formalin specimens, decidedly 
grooved, spirally coiled in contracted state, and about one half the 
length of the thorax. Peristomium forms a thick prominent ventral 
lip, opposible to thin ventral edge of prostomium. 
Branchiae (Fig. 164), three pairs, on somites 2-4, densely 
ramose, di- and tri-chotomously branched; the main stems short and 
thick, ultimate branches subulate, slightly moniliform. Branchiae 
all nearly alike in form and size ; anterior pair slightly the largest; 
all variable as to size and amount of branching. 
Setigerous lobes moderate, increasing in size from the first to the 
seventeenth (on 20th somite). Uncinigerous tori of nearly uniform 
length from 5th to 18th somites; thence gradually diminishing to 
end of body. 
Setae with striated limb on each side and curved, serrated tip 
(Fig. 165). Uncini avicular, with from 5 to 7 rows of teeth above 
the rostrum (Figs. 166-168). 
Nephridial papillae twelve pairs, on somites 4 to 15; first pair 
considerably the largest; the rest of nearly uniform size ; placed 
ventrad, and a little posterior to setigerous lobes. 
Length of larger specimen, 75 mm.; greatest transverse diameter 
of thorax, 11 mm. ; average transverse diameter of abdomen, 4 mm. 
Several specimens, collected both b} T the Columbia University 
Expedition and by Miss Robertson. The species is doubtless com¬ 
mon. No tubes were preserved. The absence of eyes in this 
species and in the preceding is remarkable. They are evidently 
wholly lacking, as I was unable to find them even in serial sections. 
44. Amphitrite spiralis sp. nov. PI. 16, figs. 169-171c. 
Form greatly elongated, abdomen slender, terete, and spirally 
coiled when out of the tube; dorsal aspect of thorax high-arched; 
ventral » slightly convex. This condition is enhanced in anterior 
portion of abdomen, where the somites are decidedly thicker on 
the dorsal than on the ventral aspect, producing thereby the spiral 
