PLATE 6. 
Fig. 1-9. DoLaBELLA AGASSIZI, sp. Nov. 
Fig. 1. Diagram showing the relations of the pallial organs; a, inner boundary of base of ia og 
b, projection of outline of posterior body-dise upon underlying organs; &k, similar projection ot ie : 
margin of parapodia, continuous in front as a low ridge; c, outline of boundary of shell; d, right margin 
of mantle, extending from between the anterior ends of the parapodial lobes backward, its posterior — 
margin reflexed dorsally at e, thence continued transversely and rising into the siphon margin at Ge 
at the posterior edge of the siphon base it becomes nearly indistinguishable, but may be followed as — 
a faint elevation to the right behind the anal opening, f, thence merging into a strong fold, o which | 
curves forward along the floor of the pallial chamber to the reproductive opening, hk, where it is con- — 
tinued around as its front margin and disappears within it (ef. Plate 4, fig. 3); i, genital furrow, extend- 
ing forward from the genital opening, h; 1, margin of the shell-foramen; n, cushion-like prominence at 
bottom of siphon. Natural size. = 
Fig. 2. Typical lateral tooth from posterior region of radula in side view, a-b, base; % tip of 
hook. X 100. 
Fig. 3. Median tooth from 12th row of radula, in face view. No indication of a hook, it beige 4 
worn away probably. X 175. 
Fig. 4. Median tooth from 13th row of radula. X 175. 
Fig. 5. Diagram of the pallial cavity; the mantle being cut away along the double line m, expos- 
ing the underlying ctenidium; a, outline of inner boundary of base of parapodia; k, projection of free — 
upper margin of parapodia upon the underlying organs continuous in front beyond the pallial thee 
b, outline of projection of the margin of the posterior body-dise; m, cut edge of mantle, the incision — 
being carried around close to the origin of the left attached margin of the mantle from the body-wall, 
thus laying open nearly the whole extent of the upper gill-cavity, except at the left posterior eas. 
where it reaches slightly farther back; af, afferent blood-vessel to ctenidium, ef, efferent blood- 
to thesame. That portion of the ctenidium lying to the right of a line joining af and ef projects ines 7 
into the pallial cavity, that to the left of the same is attached along its margin to the body-wall; hy 
common genital opening, its borders leading forward as the dotted lines to continue as the external sper- — 
matic groove, i, to the right side of the head; s, siphon; c, the cushion-like prominence at the base of ‘the 
siphon, directly below the posterior rounded opening between the parapodia; 0, osphradium. Natu- — 
ral size. 
Fig. 6. Median tooth from 20th. row of radula in side view. A slight median hook present, ina 
is worn; the anterior end of the thick basal portion is curved upward. X 175. 
Fig. 7. Median tooth from 23rd. row of radula in face view. X 175. 
Fig. 8. Median tooth from 31st. row of radula in side view. X 175. 
Fig. 9. Median tooth from 59th. row of radula in side view. The hook here reaches its greatest — 
development. X 175. 
