TETHYS—POLYNESIAN. 91 
The specimens before me are from Monterey. This species is well 
characterized by the short, poorly developed, posteriorly placed 
swimming lobes, the nearness of the tentacles to each other, the deep 
pocket-like gill cavity, and the accessory plate on the shell. <A 
small specimen before me lacks the leopard-like spotting of the out- 
side, being dirty gray with black maculz around tentacles and to- 
ward the tail. The mantle is uniform grayish, but the inner sur- 
face of swimming lobes has the marking described above. In place of 
a tube, the mantle shows only a minute pore on a very slight papilla, 
surrounded by fine radialstriz. Whether these differential features 
are specific or not remains to be decided by the examination of more 
material. 
IV. Polynesian Species. 
A considerable portion of the species from this region are not 
sufficiently known to permit the construction of any useful synopsis 
or key. 
T. prpEs Pease. PI. 20, figs. 48, 44. 
Oblong, smooth, elevately rounded above, compressed towards the 
foot. Neck long. Mantle lobes ample, thin, half the length of the 
animal, and rounded in outline. Dorsal tentacles small, grooved, 
and blunt. Oral tentacles large, strongly dilated, and united in front, 
forming a kind of veil, beneath which is the mouth. Eyes small, 
black, somewhat lateral, a little in advance of dorsal tentacles. 
Head rather flattened in front, convex in profile, with a groove ex- 
tending from the muzzle along its side and over the back of the 
animal. Siphonal tube very large and prominent, and expanding 
outwards. Branchize exposed when the mantle is thrown on one 
side. Foot narrowed anteriorly, widest posteriorly and rounded ; 
the foot is double; the posterior portion (of a circular shape) is 
smooth and projects slightly laterally and posteriorly, being quite 
distinct from the anterior portion, which is slightly rugose. Shell 
large, thin, flexible. Color brownish or brownish-olive, veined with 
dusky and clouded with white, or dusky slightly spotted with the 
same. Foot pale ash. (Pse.). 
Shell compressed, obliquely subovate, concentrically wrinkled, 
within pearly-caleareous; apex elevated, acuminated, very little in- 
curved ; upper margin sloped downwards, rounded at the end; 
