80 TETHYS-ANTILLEAN. 



acuminated, produced, reflected, incurved; upper margin sloped, 

 reflected, excavated, cuneate at the end ; outer lip anteriorly sinu- 

 ously produced ; dorsal margin rather short, reflected ; lower mar- 

 gin sloped obliquely towards the dorsal margin. (Sowb.'). 



Guadaloupe (Mus. Cuming). 



A. guadaloupensis SOWB., C. Icon., pi. v, f. 19 (August, 1869). 



" This shell is beautifully striped on the back." (Sowb.) 

 T. wiLLCOxr Heilprin. PL 35, figs. 30, 31, 32. 



Length about 11-15 cm. General form about as in T. livida. 

 Anterior head- pro cesses large, broad and prolonged downward, the 

 reflexed portion erectly triangular, the mouth between their lower 

 ends. Tentacles long, with a very short slit. Swimming lobes 

 ample, united behind only where both join the foot. Mantle with a 

 very minute tubular perforation with very short black rays around 

 it, or in some specimens the perforation is not to be seen. Mantle 

 edge posteriorly notched, and with a long tongue-like siphon lobe* 

 Opaline gland long, opening by a single large orifice about 15 mill, 

 behind genital orifice, the latter nearly as far forward as anterior 

 edge of mantle. 



Color in alcohol greenish-yellow, coarsely cloud-marbled or mac- 

 ulated on the swimming lobes, neck and head, with purplish-black j 

 mantle light, with a dark cloud at the front edge. Inside of the 

 swimming lobes olive-blackish or purple-blackish (rarely pale olive), 

 with a wide bordering series of irregular, rounded light spots at the 

 edges. 



Penis conic, decidedly enlarged at base, and black-pigmented 

 there ; a long filament projecting from the apex. 



Shell very thin, flattened, translucent ; inner layer extremely thin,, 

 a mere opalescent film ; outer layer straw colored, with many con- 

 centric whitish streaks. Apex a very small curved hook ; poste- 

 rior sinus but little concave, nearly half the shell's length, its mem- 

 braneous margin thickened and broadly reflexed across the apex. 



Length 56, breadth 40 mill. 



Little Gasparilla Bay and Marco, West Florida (Heilprin and 

 Willcox). 



Aplysia willcoxi HEILPR., Proc. Acad. Nat. Sci. Phila., 1886, p. 

 364 ; Trans. Wagner Free Inst. Sci., i, p. 130, pi. 19 (bad). 



This form agrees moderately well with d'Orbigny's A. livida in 

 some respects, but it lacks the external light speckling, and the light 



