DONAX. 335 



shorter cirrhi, all being longer in the neighbourhood of the 

 tubes than elsewhere. The tubes are separated through- 

 out, and rather long. The orifice of the branchial siphon 

 has eight principal cirrhi ramifying, or pinnated and ciliated 

 at their extremities ; the anal is surrounded by six short 

 single points. Both are of a pale orange colour, and often 

 marked above and below by deeper bands of the same tint. 

 The foot is yellowish, very large, pointed, and sharp-edged, 

 plaited at the base when retracted, and not furnished with 

 a byssal groove. The labial palps are brownish, very long, 

 triangular, and pointed. The animal is sluggish when re- 

 moved from its native locality, but is capable of active 

 motion. 



Few if any bivalves seem more universally diffused 

 around our coasts. Wherever there exists a wide range of 

 unmixed sand, there they are ordinarily met with in the 

 greatest abundance, buried an inch or two from the surface, 

 towards low water-mark. 



The D. fahagella of Lamarck (judging at least from a 

 specimen which we received in Paris from M. Recluz, as 

 having been compared with the original type) is precisely 

 identical in contour ; it is, however, distinctly sulcated, and 

 not merely striolate throughout the posterior half, and the 

 radiating striae appear entirely obsolete on the anterior 

 side. The D. venusta of Poli is equally allied, but has, 

 in all stages of its growth, strong and rather remote sulci 

 upon its hinder dorsal area. The entire absence of these 

 latter in the real D, trunculus, forms one of the most im- 

 mediately perceptible marks of its distinctness from the 

 present species. 



