256 APPENDIX. 



with extremely fine and microscopical concentric striolae, which 

 are more easily perceptible towards the margin ; occasionally, too, 

 marked upon the disk with interrupted diverging scratch-like 

 lines. Sides decidedly unequal, both of them rounded, the ante- 

 rior twice the length of the posterior one. Dorsal edges not an- 

 gulately shouldered, but descending with a moderate and convex 

 declination ; slope of the shorter side rather the more sudden. 

 Ventral edge convex in the middle, arching upwards at the shorter 

 extremity, well rounded at the other; entire within. Beaks 

 only moderately prominent, having a distinct calyx. Hinge 

 of the right valve with a strong erect simple acutely conical 

 anterior apical tooth, that points very obliquely but straightly 

 forwards, on either side of which run the lateral laminae, which 

 are nearly equidistant from the beak, and almost appear double 

 (though not actually so), from composing, with the edge of the 

 shell, a receptacle for the less distinctly perceptible laminae of the 

 opposite valve ; in this latter the sub-triangular apical tooth is 

 so contiguous to the front lateral, as almost to form a part of it. 

 Length barely a line. Dredged by Mr. Clark, from the coralline 

 region of Exmouth ; Plymouth (Barlee). 



Vol. ii. p. 186. M. PHASEOLINA. 



Mr. Hanley has recently dredged a specimen of this scarce 

 species from deep water near Castle Cornet, Guernsey. 



Vol. ii. p. 194. Crenella. 



Two well preserved specimens of Crenella faba were given to 

 Professor King by a Newcastle bird-stuffer, as taken from the sto- 

 mach of a duck, purchased at the adjoining parish of Gateshead. 

 The evidence of their indigenousness is assuredly defective ; yet, 

 since it is not impossible that examples of this boreal shell will 

 hereafter be found in the more northern islands of Scotland, to aid 

 their future identification we have appended a brief description. 



C. faba, Midler. 



Mytilus faba, Muller, Prod. Z. D. 3015, teste O. Fabric Fauna Grcenl. 

 p. 419.— Chemn. Conch. Cab. vol. viii. p. 184, pi. 85, f. 76] 



