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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 Psammodia, 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 laminz. 
The next section is a small tribe, which, with the external 
ligament and ordinary dentition of the Te/line, 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 branchiz and the 
latter only one large lamina, as in the 2nd section, but cannot 
be placed im it on account of the very different hinge. These 
are the most aberrant of the Tellinide, and immediately con- 
nect this group with the Anatinide. 
The genus Diodonta of Deshayes has been introduced into 
the British list to receive the Tellina fragilis of Linnzeus and 
authors. It seems a very useless and artificial one, based on 
the teeth, and has no new characteristic that differs from 
Tellin ernone. We dispense with the 
genus in its present form, and deposit its only species in the 
2nd section of this family. 
TELLINA, Linneus. 
Section I. The typical species. 
T. ponacina, Linnzeus. 
T. donacina, Brit. Moll. i. p. 292, pl. 20. f. 3,4; (animal) pl. K. f. 4. 
T. pygmea, Brit. Moll. i. p. 295, pl. 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 branchiz, nearly of the same 
