224 ANATINID.^E. 



T. vrr.LosirsciTLA, ^lacgillivray. 



Like T. phascolina, but rather shorter, dull, scabrous, and not at 

 all oblique ; ossicle not broader in the middle. 



Plate XVII. fig. 4, 7. 



Anatina villosiuscula, Macgilliv. Edinburgh Philos. Journal (Jamcson''s), 1827, 



p. 370, pi. 11, f. 6. 

 Thmcia ovatu. Brown, Illust. Conch. G. B. p. 110, pi. 44, f. 4. 



Although most closely allied to the T. phaseolina, this 

 little known species possesses distinctive features, which, 

 although apparently trifling, are nevertheless important 

 from their constancy. These characters had long been 

 noticed by that most accurate observer Mr. Clark, who 

 had separated it in his cabinet, under the name intermedia. 

 The general outline is nearly oblong, with a tendency to 

 angularity at the beaks ; and the valves rather thin, fragile, 

 somewhat inclined to be ventricose, but moderately unequal 

 in area and convexity, and of a dull opaque white. The 

 surface, even when examined with a lens of low power, is 

 distinctly shagreened, and is usually coarse-looking, from 

 the great irregularity of its unsymmetrically concentric 

 wrinkles of growth, and the indentations by which it is 

 not unfrequently deformed. The ventral margin is more or 

 less inclined to be rectilinear ; it is sometimes however de- 

 cidedly convex, but scarcely ever ascends much at its hinder 

 termination. The dorsal edges are both moderately and 

 nearly equally sloping, the anterior declination is ordinarily 

 the greater ; they are both nearly straight, the front being 

 scarcely convex, and the hinder hardly retuse, but with its 

 extremity a little rounded and bending downwards. The 

 sides are unequal, the anterior always being the longer (and 

 typically much so,) but the amount of inequality is very 



