TELLINA. 125 



it is of little value, if it even existed, compared with the over- 

 whelming similitude of the entire soft parts, habitudes and 

 habitats of the animals; and we may observe, that in the 

 so-called Psammobia, distinct lateral teeth are often present as 

 well as absent ; the same may be said of Tellina, but in both 

 there are almost always obsolete traces of such laminae. 



The next section is a small tribe, which, with the external 

 ligament and ordinary dentition of the Tellina, have only one 

 large amalgamated branchial lamina on each side. Lucinopsis 

 next follows, which- we have shown to be nearly a strict 

 Tellina. And lastly, Syndosmya and Scrobicularia, furnished 

 with a ligament, that is, both external and internal, besides a 

 spoon-shaped cavity for an internal cartilage, complete the 

 Tellinidan category; these may hereafter constitute two 

 distinct families, as the former has double branchiae and the 

 latter only one large lamina, as in the 2nd section, but cannot 

 be placed in it on account of the very different hinge. These 

 are the most aberrant of the Tellinida, and immediately con- 

 nect this group with the Anatinidce. 



The genus Diodonta of Deshayes has been introduced into 

 the British list to receive the Tellina fragilis of Linnaeus and 

 authors. It seems a very useless and artificial one, based on 

 the teeth, and has no new characteristic that differs from 

 Tellina at least we can discover none. We dispense with the 

 genus in its present form, and deposit its only species in the 

 2nd section of this family. 



TELLINA, Linnaeus. 

 Section I. The typical species. 

 T. DONACINA, Linnaeus. 



T. donacina, Brit. Moll. i. p. 292, pi. 20. f. 3, 4 ; (animal) pi. K. f. 4. 

 T. pygmaa, Brit. Moll. i. p. 295, pi. 19. f. 6, 7. 



Animal oblong, compressed; mantle largely open, not 

 fringed, but finely dentated. Siphonal tubes long, separate 

 from their bases, plain and simple. Foot pure white, flat, 

 broad, long, and lanceolate. On each side of the body there 

 are a pair of pale brown suboval branchiae, nearly of the same 



