112 TETHYS. 
the length of the animal, in an individual 18 lines long, the shell 
measures 8x6 lines. Penis stouter. 
Differs from <A. radiata mainly in the greater size of the shell 
compared to Jength of body. It is from the southern part of the 
Red Sea. 
VIII. Species of unknown locality. 
T. rricona Sowerby. PI. 20, fig. 42. 
Shell small, horny, brown, subtrigonal, ventricose, apex rather 
straight, acuminately produced, upper margin straight, reflected, 
obtusely angular at the end; outer lip straight, obliquely produced 
before ; dorsal margin obliquely sloped towards the lower margin, 
lower margin short. (Sowd.). 
Habitat unknown. 
A. trigona Sows., Conch. Icon., pl. 4, f. 11 (Aug., 1869). 
This species resembles Aplysia punctata in color, texture, and 
convexity, but differs from them in its triangular form. 
T. ANGUILLA Cuming. PI. 48, fig. 28. 
Shell small, tumid, strongly arched, transverse, pale horn; apex 
rounded, small, incurved ; upper margin very short, deeply excava- 
ted, acuminated at the end; outer lip obliquely produced; dorsal 
margin round; lower margin oblique, widely excavated. (Sowd.). 
Habitat unknown. 
A, anguilla Cuming MS., Sows., Conch. Icon., pl. 6, f. 22. 
A species with very convex shell. 
Unrecognized and spurious species. 
Laplisia viridis Bosc, 1802, Hist. Nat. Vers, i, p. 64, pl. 2, f 4 
(see also Nouv. Dict. d’Hist. Nat., pl. 5, f. 23, and Rang, p. 73), de- 
scribed from the harbor of Charleston, S. C., belongs, in my opin- 
ion, to the nudibranch family Elysiide. 
Aplysia sicula Swainson, Treatise on Malacology, or Shells and 
Shell-fish, p. 247, fig. 45, (1840). This Sicilian species drawn in 
outline from life, is entirely unrecognizable from Swainson’s sketch, 
by which alone it is known. 
Aplysia unicolor Risso, Journ. de Physique, etc., Ixxxvil, p. 374. 
