122 DONACIDJE. 



DONACID^E. 



If this family had only consisted of the genus Donax, we 

 would have united it to the Tellmidce', but as it is conjoined to 

 Ervilia, a more aberrant genus, we adopt it. The siphons 

 appear to be shorter than in the Tellinidce, and their cilia of a 

 more complicated structure ; the dentition is also less simple. 

 There are only three undoubted British species, two in Donax, 

 D. anatinus and D. politus the D. trunculus is probably 

 exotic and one in Ervilia, the E. castanea. 



DONAX, Linnjeus. 



D. ANATINUS, Lamarck. 

 D. anatinus, Brit. Moll. i. p. 332, pi. 21. f. 4,5,6; (animal) pi. K. f. 1. 



Animal elongated, of a purplish- red or yellow ; mantle open 

 on the ventral range, with double margins, the one short, with 

 sinuated or scalloped edges; the other and outer is clothed 

 with three rows of fringe, the two inner being two sizes of 

 moniliform white beads ; the outermost or third row has short, 

 close-set, fine filaments of similar colour, altogether presenting 

 a very elegant appearance. The siphons are of the same 

 length, and, when fully exserted, are not more than half an 

 inch; they do not put on a cylindrical aspect, but appear 

 laterally compressed; they are separate from the bases, and 

 taper gradually to their terminations, which are bordered 

 with very pale orange colour ; the anal siphon is rather the 

 smallest, and furnished with about six white cirrhi; the 

 branchial has 8-10 longer ones, which are fimbriated at the 

 sides, besides plain ones interspersed; when the cirrhi are 

 withdrawn, the terminations of the tubes have a truncate and 

 naked aspect ; a good lens must be used to see their minute 

 developments. The foot is yellow or orange, especially when 

 the animal has been immersed in hot water, very large, flat, 

 bevelled to a sharp edge and lanceolate point when fully 



