TETHYS-ANTILLEAN. 81 



markings along the inner edge of swimming lobes are not nearly so 

 regular as in livida. The more important structural characters of 

 the latter, however, are still unknown. The whole scheme of color- 

 ing is unlike Rang's protea, which differs moreover in characters of 

 the shell. That of T. willcoxi is uncommonly flat, with extremely 

 slight, iridescent calcareous layer and wide cuticular borders. The 

 description is from alcoholic specimens, as was that of Heilprin. 



Var. PERVIRIDIS. PI. 55, figs. 1, 2, 3, 4. 



Length 14 cm. when living, 11 contracted in alcohol. Body 

 large, much swollen behind. Anterior processes broadly folded 

 above ; tentacles conic and slit as usual. Swimming lobes very 

 ample, free, united only at their insertion at the tail. Mantle large, 

 its perforation extremely minute, with thickened edges but not 

 tubular, surrounded by fine radial wrinkles, visible only under a 

 lens (fig. 2, enlarged), the papilla being less than 1 mill. diam. 

 Posterior right margin of mantle excised and folding into a short 

 excurrent channel. Genital opening well forward, about as figured 

 for T. willcoxi. Opaline gland 20-22 mill, behind genital pore, 

 projecting externally as a pedunculated oval body in the type speci- 

 men (fig. 1), but perhaps evaginated, in which case it would have 

 one large orifice. 



Colors in life clear green on the head and tentacles, the 

 swimming lobes olive-green with a coarse-meshed reticulation of 

 black, subdivided by fine veins, irregularly maculated all over with 

 light green, these spots having groups of white dots ; the extruded 

 mouth parts purple. In alcohol (for 10 months) it is grass green 

 with black reticulation on the sides, caused by massing of the black 

 veins through contraction ; foot clear green ; mantle green with some 

 whitish clouds; inner surface of swimming lobes green and dirty 

 whitish, marked with black in the sinus between lobes and body, 

 the black extending well on the lobes toward the hind end ; no no- 

 ticeable black markings at inside edges of lobes. 



Shell large, depressed, thin, yellowish, with fainter concentric 

 growth wrinkles and coarse faint radii. Calcareous layer thin, the 

 cuticular layer projecting far beyond it. Apex only moderately 

 incurved, the epidermis reflexed across it as in T. willcoxi. Sinus 

 shallow and wide. Length 60, breadth 52 mill. 



Cape May, New Jersey (H. Lemon). 



