TAPES. 353 



invariably the microscopical strise : colour yellowish- white, 

 often painted with two or three reddish-brown or purplish 

 rays of different widths, which are seldom entire, being gene- 

 rally interrupted and divided into streaks, zigzag markings, or 

 spots of a most diversified kind ; the rays frequently appear 

 white, owing to the greater breadth of the darker bands ; 

 some specimens, as in T. aureus, are of a uniform pale yellow 

 or milk-white : epidermis horny, rubbed off in nearly every 

 part : margins obliquely but not much rounded in front, sharply 

 curved and produced on the anterior side, behind which the 

 line from the beaks is nearly straight, produced and wedge- 

 shaped on the posterior side, which is obliquely truncate and 

 ends in a blunt point, straight on the dorsal side in the young 

 but sloping gradually and with a slight curve in the adult : 

 beaks small, somewhat inflected, and close together ; umbonal 

 area not prominent : lunule lanceolate, longer than in T. aureus 

 but similar in other respects : corselet indistinct : ligament 

 rather long, yellowish-brown, wholly exposed, contained in a 

 marginal groove : hinge-line and hinge-plate as in the last spe- 

 cies : teeth, in the right valve three erect cardinals, of which 

 the posterior is the smallest, triangular, and set obliquely, the 

 middle cardinal is the largest and double or cloven ; the left 

 valve has the same number of cardinals, the smallest of which 

 is on the anterior side and set obliquely, and the other two are 

 double ; laterals indistinct : inside rather glossy, with a purplish 

 or orange tinge towards the beaks in bright-coloured speci- 

 mens: scars as in T. aureus. L. 1*6. B. 1*9. 



Yar. 1. Sarniensis. Shell thicker, less produced at both 

 ends and consequently of an oval shape. V. Samiensis, Turt. 

 Dith. p. 153, tab. 10. f. 6. 



Var. 2. elongata. Shell more produced and pointed at the 

 posterior end, being consequently more oblong and broader in 

 proportion to its length. 



Habitat : Every part of the British coasts, in sand 

 and among nullipore3, from the shore to 145 fathoms, 

 at which latter depth it was dredged by Capt. Beechey 

 off the Mnll of Galloway. " Garnsey " was the first 

 recorded locality, as appears from Lister's ' Historia 

 Conchyliorum/ It occurs in all our upper tertiaries 

 from the Belfast deposit (Grainger) and glacial beds at 



