100 TETHYS-AUSTRALASIAN. 



Aplysia norfolkensis SOWB., Conch. Icon., pi. 10, f. 42a, b (Aug., 

 1869). ANGAS, 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. (Sowb.) 



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. (Sowb.) 



Australia (Sowb.) 



Aplysia concava SOWB., Genera of Shells, fig. 3. A. concava 

 SOWB., Conch. Icon., pi. 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 reflected 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 9? 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 SOWB., Conch. Icon., xvii, pi. 3, f. 8a, b (Aug., 

 1869). ANGAS, P. Z. S., 1877, p. 190. Aplysia hyalina SOWB., t. 

 c., pi. 4, f. 13a, b, ANGAS, I. c. 



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 (pi. 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- 



