PLEUROBRANCHUS. 203 



and immersed just behind the tentacles. Oral veil large, notched in 

 front, and extended laterally in tentacular shape. Branchial plume 

 free, on the posterior half of right side, plumules tripinnate. 

 Length two inches. 



Cream color, irregularly spotted, both as to shape and size, with 

 purple-red. A few similar spots on the head, veil and gill. Mantle 

 and foot narrowly edged, and extremities of the tentacles tinted 

 with the same color. (P$e.). 



Tahiti, under stones, in upper region of laminarian zone (Pse.). 



P. ovalis PSE., Amer. Journ. Conch., iv, 79, pi. 9, f. 3 (1868). 



The shell is very fragile. We have but an imperfect specimen, 

 which is of the usual shape and size. (Pse.). 



P. TESSELLATUS Pease. PI. 47, figs. 20, 21. 



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 dis- 

 tance behind the mantle when the animal is in motion. Oral veil 

 subtriangular, somewhat produced laterally. Cream color, mantle 

 reticulated with opaque 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. 

 Shell ? (Pse.'). 



Polynesia. 



P.- -f PSE., P. Z. S., 1861, p. 245. P. tessellatus PSE., 

 P. Z. S., 1863, p. 510 ; Amer. Journ. Conch., iv, p. 80, pi. 9, f. 4. ' 

 No locality is given by Pease for this species. 



P. PELLUCIDUS Pease. 



Mantle oval, smooth, convex above, not covering the foot behind, 

 and the margins slightly undulated. Tentacles short, stout, smooth, 

 truncated and grooved. Oral veil large, broad, emarginated in the 

 front, which part is much prolonged laterally, so as to give it a 

 triangular form. Eyes sessile, immersed at the posterior inner bases 

 of the tentacles. Foot large. Branchiae on the right side, tripin- 

 nate, elongate and exposed. Color whitish translucent, and the 

 whole upper surface of the mantle, with the exception of that por- 

 tion covering the shell, minutely reticulated. Shell rather large, 

 oblong-ovate, whitish horn color, thin, fragile, pellucid, and rather 



