80 AMERICAN JOURNAL 



Remarks. — Station under stones, at low water-mark. 



The shell of this species (and of a few others to bo hereafter 

 described) differs considerably from the usual form, in being very 

 narrow posteriorly, approaching that of genus Syphonota. 



Pleurobranciius tessellatus, Pease. — Plate 9, fin-. 4. 



Description. — Testa ? 



Animal oval, subpellucid, smooth, white reticulations on upper 

 surface of the mantle, slightly raised. Mantle rounded behind, 

 slightly concave in front. Foot thin, oblong, projecting a short 

 distance behind the mantle when the animal is in motion. Oral 

 veil subtriangular, somewhat produced laterally. Cream color, 

 mantle reticulated with opake white, and irregularly spotted with 

 reddish-brown, the larger spots more or less dotted with white, 

 under edges of the mantle and margin of foot dotted with reddish- 

 brown, and a larger spot of same color on the upper posterior 

 end of the foot. 



Piiyllidia nigra, Pease. — Plate 9, fig 5. 



Description. — Mantle oblong-elliptical, widest in the middle, 

 similarly rounded at each end, convex above, closely ridged 

 longitudinally, ridges prominent, rather rugose, angular on their 

 upper edge and disposed as follows : one median extending from 

 between the tenacles to the anal duct, one from each tentacle, 

 passing toward, but not quite reaching, the above-mentioned 

 duct, marginal ones smaller, interrupted or bifurcate and varying 

 in number. Cervical tentacles rather small, erect, cylindrical, 

 clavate, tips truncate, issuing from tubular cavities, retractile, 

 laminae fine and oblique. Anal duct far posterior, retractile in 

 tuberculated cavity. Foot rather narrow, elongate, tapering 

 posteriorly to a rounded tip, projecting a short distance beyond 

 the mantle. Labial palps stout, cylindric, somewhat produced. 

 Branchiae extend quite around the body, between the mantle and 

 foot. Genital orifice on the right side at the middle of the an- 

 terior half of the body. Ridges and tubercles tawney-pink, in- 

 terspaces jet black, tentacles black behind, tawney-pink in front. 

 Beneath pale lead color, with a shade of carnation, and minutely 

 freckled with leaden-green. Branchiae dark lead color. 



Dimensions. — Length one inch and three-quarters. 



Ilab.— Tahiti. 



Remarks. — Station on sea weed, in shallow water. Motions 

 languid. Emits a fetid odor. 



