402 tellinidjE. 



of Tellina (e. g. T. donacina) in its cuneiform shape; 

 but the dentition is more complicated. The ligament 

 is placed at the smaller end of the shell, as in all the 

 other genera belonging to this family. Under the above 

 circumstances I have thought it best to unite the Dona- 

 cida with the Tellinida?, considering also that we have 

 only Donax to dispose of. 



The habits of the present genus are gregarious, and 

 usually littoral, although in suitable localities, where a bed 

 of sand extends out to sea, the Donaces may be found at 

 some depth. According to M. Pictet it did not make its 

 appearance until the Tertiary epoch. Chemnitz called it 

 Serrida, and Poli Peroncea. Lamarck's genus Capsa i3 

 described as having no lateral teeth, and only differing in 

 that respect from Donax : the late G. B. Sowerby added 

 another character, viz. a smooth inside margin, and in- 

 stanced our D. politus as one of the types ; but that 

 species certainly has lateral or side teeth. 



A. Inside margin strongly notched. 



1. Donax vitta'tus*, Da Costa. 



Ouneus vittatiis, Da Costa, Brit. Conch, p. 202, pi. xiv. f. 3. D. anatmus, 

 F. & H. i. p. 332, pi. nri. f. 4, 5, and (animal) pi. K. f. 7. 



Body elongated, purplish-red or yellow: mantle open for 

 two-thirds of its extent, thickened at the edges and having a 

 double margin ; one margin is short, with sinuous or scalloped 

 edges ; the other and outer one is fringed with three rows of 

 cirri, the inner two consisting of moniliform white beads of two 

 sizes, and the outermost or third row having short, close-set, 

 fine filaments of the same colour ; the cirri become longer and 

 stronger as they approach the posterior side: tubes trans- 

 parent, of equal length, and when fully exserted not more than 

 half an inch long ; incurrent tube ornamented with eight lon- 

 gitudinal ciliated lines of an opaque-white colour, which give 



* Banded. 



