TETHYS—ANTILLEAN. 81 
markings along the inner edge of swimming lobes are not nearly so 
regular as in /ivida. 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 7. 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. willeoxt. 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), 
