100 TETHYS—AUSTRALASIAN. 
Aplysia norfolkensis Sows., Conch. Icon., pl. 10, f. 42a, b (Aug., 
1869).—Awnaas, P. Z. S., 1877, p. 190. 
The auricle produced by the reflected dorsal margin is more ex- 
panded in Aplysia concava than in this similarly shaped but differ- 
ently colored shell. (Sowd.) 
T. concava Sowerby. PI. 43, fig. 27 (enlarged). 
Shell small, straw-colored, thin, ventricose, transverse, smooth, 
white within; apex small, rounded, strongly incurved, subauricu- 
lated on both sides, upper side concave, short; dorsal margin re- 
flected, elevated, oblique, sloped towards the outer lip. (Sowbd.) 
Australia (Sowb.). 
Aplysia concava Sows., Genera of Shells, fig. 38.—A. concava 
Sows., Conch. Icon., pl. 6, f. 24a, b. 
Aplysia anguilla is more transverse, and Aplysia rosea more tri- 
angular than this species, although they nearly resemble it; the 
apex is auriculated, and the reftected lateral margins near it 
(Sowb.) 
Much like elongata Pse., norfolkensis Sowb., and parvula Guild. 
I suspect it to be identical with one of the latter species, notwith- 
standing the locality given by Sowerby. The original figure meas- 
ures 92 mill long. 
T. excavaTa Sowerby. PI. 58, figs. 32, 33. 
Shell pale, thin, subquadrate, scarcely oblong, concentrically 
striped, ventricose, within thinly testaceous, apex not prominent, 
thin, roundly incurved; upper margin short, scarcely excavated, 
square at the end, outer lip rather straight; lower margin square ; 
dorsal margin very thin, convex. (Sowb.) 
Port Jackson (Angas), 
Aplysia excavata Sows., Conch. Icon., xvii, pl. 3, f. 8a, b (Aug., 
1869).—Aneas, P. Z.S., 1877, p. 190 —Aplysia hyalina Sows., t. 
e., pl. 4, f. 18a, b,— Aneas, Ll. ¢. 
Aplysia excavata and hyalina were described from shells only, and 
these are so similar that I believe them to belong to one species. 
The description of hyalina is a follows : 
Aplysia hyalina (pl. 58, figs. 30, 31). Shell round, pellucid, hya- 
line, ventricose, thinly concentrically ridged ; back convex, with a 
sulcus near the margin ; apex depressed, rounded, incurved ; upper 
margin elevated, rounded at the end; outer lip convex ; dorsal mar- 
