MEGATEBENNUS. 187 



This species is thinner, more finely striated than F. scutellum 

 Gmel. and has proportionately far smaller orifice. 



It is separated from F. mutabilis var. sagittata by the form of the 

 shell-edge, which is curved at the ends, so that the shell rests on the 

 side-margins alone when placed upon a plane surface. 



M. nigrita Sowerby. PI. 44, figs. 97, 98. 



Shell oblong-oval depressed, the orifice nearly central or a little 

 behind the middle, large, oblong, nearly one-third the length of the 

 shell. Surface finely radiately striated and with uneven growth- 

 striae ; dark brown in color, obscurely rayed with darker. 



The form is oblong, both extremities decidedly elevated, so that 

 the shell rests upon the sides when standing upon a plane. The color 

 is " dark ash-brown, obscurely black-rayed." The inside is bluish ; 

 orifice surrounded by a narrow marginal callus ; edge of shell blunt, 

 smooth. Length 14-16, breadth 9 J, alt. 4 mill. 



South Australia; Tasmania. 



F. nigrita Sowb. P. Z. S. 1834, p. 127 ; Conchol. Illust., f. 47.— 

 Reeve, Conch. Icon., f. 41. — Sowb. Thes. Conch., iii, p. 203, f. 196. 



A dark colored species, elevated at both ends, with larger perfora- 

 tion than F. scutellum Gm. (F. hiantula Auct.), and a narrower mar- 

 ginal callus around the perforation. It is less compressed at the 

 sides than most scutellum. 



M. concatenata Crosse & Fischer. PI. 22, figs. 40, 41, 42. 



Shell oval, depressed, without radiating ribs, very slightly com- 

 pressed laterally, ornamented all over the outside with an elegant 

 pattern of little rounded pits, becoming oval near the margins. Per- 

 foration large, oblong, a little over one-fifth the length of the shell. 



The outline is oval, depressed ; color pure white ; sculpture look- 

 ing like the base of a honeycomb, but the pitting somewhat irregular 

 usually. Inside with a narrow callus rim around the perforation ; 

 muscle-impression not impressed, close to the margin. The shell is 

 rather thin. 



Length 15, breadth 10*, alt. Si mill. 



Length 18, breadth 13 mill. 



Port Lincoln, S. Australia, and Lake Macquarie, N. S. Wales. 



Fissurella concatenata C. & F. Journ. de Conchyl. xii, 1864, p. 

 348 ; I. c. 1865, p. 41, t. 3, f. 1-3.— Angas, P. Z. S. 1865, p. 184. 

 The peculiarly pitted surface is highly characteristic. 



