188 MEGATEBENNUS. 



M. TRAPEZINA Sowerby. PI. 62, figs. 10, 11, 12. 



Shell short, quadrate, the angles rounded, fissure a little in front 

 of the middle, rather large, elliptical, one-fifth the length of the shell 

 or a little more ; concentric striae fine, regular, more obvious than 

 than the radiating ones. Color a light fawn tint, rayed with brown. 



The outline is unusually square in adult shells (but the half-grown 

 are oval), the front margin being abruptly truncated, and strongly 

 arched upward. The posterior end is broadly rounded, and also a 

 little curved upward. The surface is sculptured all over with 

 beautifully fine and regular concentric strise, decussated by equally 

 fine radiating striae, scarcely visible except near the summit. The 

 color is a very delicate fawn or cream, upon which rays and lines of 

 light, but rich brown, radiate toward the margins. Inside of a rather 

 soiled white, the perforation bordered by a strongly defined callus, 

 which is bounded by a roughened tract. The muscle-impression is 

 very deep, close to the edge of the shell, its enlarged anterior ex- 

 tremities connected by a roughened scar. The edge of the shell is 

 blunt. Length 25, breadth 20 , alt. 7 mill. 



Guiehen and Holdfast Bays, S.Australia; Tasmania; New South 

 Wales, Australia. 



F. Javanicensis LAMARCK, An. s. Vert, vi, pt. 2, p. 14. Deles- 

 sert, Kec. de Coq., t. 24, f. S.F. trapezina SOWB. P. Z. S. 1834, p. 

 126. F. scutellum (GRAY in coll. Brit. Mus.) SOWERBY, Conch. 

 Illustr., p. 5, f. 34. F. scutella Gray, REEVE, Conch. Icon., f. 33. 

 Fissurellidea scutella G. B. SOWB. JR., Thes. Conch, iii, p. 203, f. 

 207. ANGAS, P. Z. S. 1878, p. 868. (not Patella scutellum GMELIN). 

 Fissurella tasmaniensis BONNET, Rev. et Mag. de Zool., 2d ser. 

 xvi, 1864, p. 72, t. 6, f. 5. 



A squarish species, much shorter than F. scutellum and beautifully 

 striate concentrically. The coloration is peculiar. 



This shell was first described by Lamarck, and should perhaps 

 bear the name imposed by him. I have rejected it because the 

 species does not occur within a thousand miles of Java, and because 

 he described a young shell. Sowerby's F. Javanicensis (Conch. 

 Illust., f. 12) is quite a different thing, probably a form of F. scutel- 

 lum Gmel. The locality given by some authors, Cape of Good 

 Hope, requires confirmation. 



