210 REPORT— 1866. 



pressed, oval, widest in the middle. Surface minutely punctate. Colour 

 purplish brown. Length J- in. 



Hah. The Minch, 45-60 fathoms ; and in shell sand from Eoimdstone. 



Baikdia complanata, n. sp. 



Subreniform, highest in the middle, greatest height equal to about half the 

 length ; anterior extremity evenly rounded, posterior narroAved and some- 

 what obliquely rounded. Dorsal margin boldly arched, highest in the 

 middle and sloping steeply behind ; ventral gently sinuated in front, and 

 slightly convex behind. Outline, as seen from above, compressed, oval; 

 greatest width in the middle, and equal to about one-third of the length. 

 Shell smooth, colour pale ochreous or w^hite. Length J^- in. 



Hah. The Minch, 45-60 fathoms. 



CVTHEEE (?) SUBPLAVESCENS, U. Sp. 



Oval or subtriangular, highest in the middle, greatest height eqiial to 

 more than half the length, rather tumid. Extremities rounded and nearly 

 equal in width. Superior margin arched, somewhat gibbous in the middle, 

 inferior margin rather convex. Seen from above, oval, widest in the middle, 

 obtusely ])ointed in front, rounded behind, width equal to nearly half the 

 length. Shell smooth, pale j-ellow, finely and closely punctate. Length 



Hah. The Minch, 45-60 fathoms. 



Cttheke ejiaciata, n. sp. 



Qiiadrangular, higher in front than behind, length equal to more than 

 twice the height. Anterior margin slightly rounded, often fringed with 

 eight or nine teeth ; posterior narrowed, cmarginate above, produced and 

 toothed below. Superior and inferior margins Hcarly straight. Outline, as 

 seen from above, oblong, widest behind, nearly thrice as long as broad. 

 Surface marked with large pits arranged longitudinally ; along the middle of 

 the valve a conspicuous elevated rib ; a less distinct ridge within the ventral 

 margin, and another smaller obhque rib behind the antero-dorsal angle. 

 Length J^y in. 



Hah. Hebrides (locality doubtful), and many other places in Great 

 Britain and Ireland. 



Cytheee complexa, n. sp. 



Ehomboidal, excessively tumid below, somewhat higher in front than 

 behind ; greatest height equal to two-thirds of the length. Anterior margin 

 rounded ; posterior obliquely truncate below, and produced into a short blunt 

 beak above ; dorsal margin straight, slightly sloping from the front ; ventral 

 margin straight. Seen from above the outline is triangular, with deeply con- 

 stricted sides, pointed in front, and centrally mucronatc behind. Surface 

 rather coarsely reticulated; one tubercle situated near the anteiior hinge, and 

 two larger ones with an intermediate connecting ala a httle above the ventral 

 margin. Length -^ in. 



Huh. Uncertain (probably Loch Alsh). 



Oytherura ucjiilis, n. sp. 



Subrhoraboidal, nearly equal in height throughout ; anterior niiirgln ob- 

 liquely rounded, sloping steeply above ; posterior obliquely truncate. Supe- 

 rior margin very gently arched, sloping steeply behind, inferior straight or 



