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 maculae 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 radial striae. 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. BIPES Pease. PI. 20, figs. 43, 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. Branchiae 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-calcareous; apex elevated, acuminated, very little in- 

 curved ; upper margin sloped downwards, rounded at the end ; 



