91 



Magasella vercoi, n. sp., Blochmann. PI. xxvii., tigs. 1 to 5. 

 Shell small, in outline of a slender pear shape, higher 

 than wide, remarkably thickwalled, light to dark dull coral-red, 

 with a conspicuous finger-shaped hinge process. The greatest 

 width is somewhat in front of the centre. Beak stout, 

 rather strongly bent dorsalwards, and then obliquely trun- 

 cate, with a moderately large hole. Its sides are rounded, 

 and towards the deltidial plate are finished off in a sharp 

 edge. Deltidial plates large, joining together widely. 

 Lateral edge of the ventral valve in the neighbourhood of 

 the teeth raised dorsally in a low point, further forwards 

 curving ventrally. Front edge distinctly convex dorsally. 



Both valves are nearly equally deep. The accremental 

 stria? are in both quite distinct. To the square millimetre 

 there are about 216 pores, the inner diameter of which 

 amounts to 20 /a. Their outer opening is oval, and measures 

 25-30 jut by 35-40^. Both valves are in their hinder part 

 very massive. The thickness of the ventral valve at the beak 

 amounts to about 0'6 mm. This circumstance, together with 

 the somewhat thickened and in many examples distinctly 

 contracted edge, shows with certainty that it has reached a 

 full-grown stage. The colour is a dull lighter or darker 

 coral -red. 



The dorsal valve bears conspicuous tooth sockets, the 

 free wall of which posteriorly projects over the hinge in a 

 triangle. In front of the hinge lies a blunt finger-like hinge 

 process. Under this, looking from the inner side, i.e., also 

 dorsal, appears a hinge-plate, depressed in a furrow-like man- 

 ner in the middle. The hollow space generally existing 

 between the hinge-plate and the wall of the valve is filled up. 

 To the hinge-plate is joined on a stout median septum, reach- 

 ing as far as the middle or even somewhat further forwards. 

 Its free edge is strongly curved from before backwards, corre- 

 sponding to the curve of the valve. The brachial apparatus 

 begins with short crura, which bear wide triangular incon- 

 spicuous crural processes. The descending limbs reach the 

 median septum widening towards the front, and descending 

 ventrally unite widely with this, run a short distance back- 

 wards towards the hinge, and are then united by a bridge 

 somewhat variable in width and position. The brachial appa- 

 ratus is colourless, or very pale-red. The anterior portion 

 of this is in its general form somewhat variable. 



Dim. — The size of the largest example before me and 

 of another is: — 



Length, 7*5 mm. and 6*5 mm. 



Breadth, 4'0 mm. and 3'7 mm. 



Thickness, 4*8 mm. and. 4'4 mm. 



