OF THE 



TETHYS-WEST AMERICAN. 89 



species seems very nearly allied to this, unless it be the Antillean 

 form of T. dactylomela. 



T. ROBERTSI Pilsbry, n. sp. PI. 55, figs. 4, 5. 



Length (of alcoholic specimen) 11 cm. General form slender and 

 lengthened ; the tail unusually long, depressed, and extending far 

 beyond posterior insertion of the swimming lobes. Neck and head 

 elongated, the mouth in a vertical fissure as usual. Rhinophores 

 conical, slit about half-way down, the minute, rudimentary eyes 

 situated outward from them, but only a trifle anterior to the front 

 of their bases. Swimming lobes wholly free from anterior to posterior 

 insertions, moderately ample. Mantle having a minute, subcentral, 

 conic tube ; its free right border wide, produced in a folded lobe 

 posteriorly, forming a rather long excurrent siphon. Opaline 

 gland opening by a single large orifice. Foramen of the penis situ- 

 ated far forward, anterior to and below the right anterior tentacle, 

 above the front edge of sole. Foot fleshy, the sole wide, emarginate 

 in front. 



Color (in alcohol) dirty light olive, very minutely wrinkle-retic- 

 ulate with black-brown in places, forming a large cloud on the out- 

 side of each swimming lobe, another occupying the face ; sole black- 

 ish ; inner surface of swimming lobes blackish below, lightly stained 

 in places outwardly. Mantle clear olivaceous over the shell, the 

 free border and siphon blackish. 



Shell thin, fragile, with very slight calcareous layer ; buff" outside ; 

 apex hardly curved, with a narrow reflexed margin. Sinus long, 

 nearly straight, margined. Length 28, width 22 mill. 



West coast of Mexico (Dr. W. H. Jones). 



Notable features of this species are the unusually posterior eyes, 

 anterior male genital pore, wholly free swimming lobes, and especi- 

 ally the long tail. The shell has a very thin calcareous layer, and 

 the sinus is nearly straight. The type was in a bottle with Dolabella 

 calif ornica Stearns, which it resembles in color, at least in the 

 alcoholic condition. The specific name is in honor of Mr. S. RAY- 

 MOND ROBERTS, whose services as an officer of the Conchological 

 Section during a long series of years, are well known and appreciated 

 by conchologists. 



T. CALIFORNICA Cooper. PI. 56, figs. 13, 14. 



Length 37?, breadth and height 12 cm. (Cooper). Length of 

 alcoholic specimen described below 11 cm. Body obese, the ante- 



