TETHYS-INDIAN OCEAN. 107 



b. Surface marked with ocellated spots, 



lineolata, oculifera, argus. 

 bb. Not ocellate. 



c. Mantle with a subcentral tube ; swimming lobes am- 

 ple. 

 d. Olive-brown with pale spots ; mantle reddish, 



maculata. 



dd. Dark green, coarsely marbled with dark, and 



with many groups of pale dots, tigrina. 



cc. Characters of mantle unknown, tigrinella, nodifera. 



ccc. Mantle with a subcentral perforation ; lobes ample ; 



uniform dark green, Juliana. 



T. NIGROCINCTA Martens. PI. 17, figs. 14, 15, 16. 



Length, in spirit, 17 mill., alt. 11, breadth 7 mill. Smooth, light 

 brown, the free margins of the swimming lobes, the edge of the sole, 

 and the margin of the rather large hole in the mantle, black, mostly 

 continuous, sometimes rather spotted. 



Shell strongly convex, comparatively large, of a beautiful amber- 

 yellow, shining reddish through the mantle ; spoon-shaped, with 

 shallow sinus and strongly incurved apex ; 11 mill, long, 8 wide, 

 5 high, occupying more than half the total length of the animal. 

 (Martens.) 



Fouquets, Mauritius (Mobius). 



Aplysia nigrocincta MARTENS, in Mobius' Beitr. zur Meeresfauna 

 der Insul Mauritius u. der Seychellen, p. 307, pi. 21, f. 3 (1880). 



" Reminds one of A. virescens Risso, pi. 19, f. 5, of unknown lo- 

 cality, but coloration and form of the shell are different." This 

 species is allied to T. parvula, T. elongata, etc., species with large 

 mantle foramen and very convex shell. 



T. MACULATA Rang. PL 60, figs. 49, 50, 51, 52. 



Length 9 cm. Oblong, much swollen, depressed at the base, 

 elongated in front and obtuse behind, smooth. Swimming lobes of 

 moderate size, the dorsal cavity very open. Mantle reddish, with a 

 long excurrent siphon and a tubular foramen. Gills roseate. 



Color, externally, brown-olivaceous, with some pale spots, the 

 dorsal cavity reddish. 



Shell oval, very concave, membranous with very little calcareous 

 substance ; sinus small and nearly posterior ; apex a little recurved 



