GENA. 39 



Known to me only by the above translated description and the 

 original figures. Adams identified this species with one I believe to 

 be entirely different. 



G. strigosa A. Adams. PI. 55, figs. 31, 32 ; pi. 2, figs. 8-16. 



Shell depressed, Haliotis-shaped, oval, the right side straightened, 

 the left strongly curved ; aperture angled above, narrower than the 

 shell, its margins arched, so that when placed on a plane the shell is 

 supported by its extremities. Surface very densely and finely 

 spirally striated all over, these fine, even stria? decussated by oblique 

 growth-lines ; color various. 



The spire is very short, consisting of a minute projecting cone of 

 about 3J-4 whorls; it is decidedly more elevated and more remote 

 from the margin than in G. planulata, and the body of the shell is 

 more convex than in that species. The surface is shining, very 

 finely, closely striated. The color is excessively variable, but in all 

 the mutations there is a white tract along the columella with, usually, 

 a series of red flammules bordering it. The aperture is not bilater- 

 ally symmetrical as in G. planulata, but angled at the termination of the 

 straightened outer lip, the columella very much arched. The interior 

 is nacreous, its reflections chiefly silvery and green, but sometimes as 

 fiery red as in G. planulata. 



Length 18, breadth 10* mill. ; convexity when resting on a plane, 

 5 mill ; aperture, length 14], breadth 8 | mill. 



Length 16, breadth 9 mill. ; convexity 4 J mill. ; aperture, length 

 12-], breadth 7 mill. 



Port Jackson, Australia. 



G. strigosa Ad., P. Z. S. 1850, p. 37 ; Thes. Conch, ii, p. 830, t. 

 173, f. 11, 12.— G. nigra Ad., Thes. Conch., p. 829, f. 14-16 (not of 

 Quoy and Gaim.). — G. plumb ea Ad., P. Z. S. 1850, p. 37; Thes. 

 Conch., f. 13. 



The species of Gena are difficult to distinguish without fuller 

 descriptions or better figures than those in the Thesaurus, though the 

 latter are good. Under the head of strigosa I have here grouped 

 shells agreeing with Adams' strigosa, nigra, and plumbea. These 

 three seem to represent merely extreme color-patterns in a species so 

 variable that scarcely two of the twenty specimens before me are 

 alike. 



The typical strigosa (pi. 55, f. 31, 32) is " rather depressed, the 

 back equally convex, striated all over, olivaceous varied with white 



