l6 OPISTHOBRANCHIATA OF BRAZIL 



men of 7.0 mm., the band of pigment itself ranging up to 3.0 

 mm. in width. The inner surface of the parapodial lobes bears 

 several branching bands of black, running in a generally vertical 

 direction, near the thin margins, with occasional isolated blotches 

 of pigment between them, and below merging into the black to 

 greenish black area at the bases of the parapodia. Between the 

 posterior ends of the parapodia is situated a median longitudinal 

 dark band, which dilates posteriorly into a broad crescentic spot, 

 the points of which are prolonged upward for a short distance 

 along the inner face of the margins of the parapodia. The dorsal 

 surface of the mantle is marked with irregular blotches of black, 

 tending to form a series of incomplete rings. The under surface 

 of the mantle is yellowish brown, the branchia brownish black, 

 or nearly free from color. 



Parapodia. The parapodia are prominent and high, their 

 margins thin. The posterior half of the mantle is rolled into an 

 erect tube, the siphon, the thin crenulate upper margin of which, 

 in its slightly contracted state reaches just below the margins of 

 the parapodia. 



Shell. About midway of the length of the mantle in the 

 median line is a single minute opening, borne upon a well marked, 

 short cylindrical papilla, communicating with the shell sac, or 

 mantle cavity. The shell is of good size, rather convex, very 

 thin and translucent, but slightly calcareous, externally very pale 

 yellow in color. In all the specimens unfortunately it was some- 

 what broken, the inner calcareous surface being reduced usually 

 to fragments. The thin membranaceous margin of the shell pro- 

 jects beyond the calcified portion beneath, its anterior and right 

 borders are rounded, the posterior border concave, the beak much 

 thickened, triangular and recurved. In general it is similar to 

 the figures of Rang for the species. Length 23 mm., width 16 

 mm., in an animal of 70 mm. total body length. 



Tentacles. The tentacles and head region generally are 

 more or less contracted in all the specimens. In the best preserved 

 ones the posterior tentacles, or rhinophores are slender, auriform, 

 the external slit being carried down posteriorly nearly to the base 

 of the organ. 



The anterior tentacles are much broader, stout, auriform, 

 triangular in general outline, their outer margins being con- 



