106 
MOLLUSCA. 
[Mactracea. 
4. Amphidesma truncata, pi. XLII, f. 4. 
Ligula ti'uncata, First Ed., pi. 14, f. 4 ; Amphidesma trun- 
catum, Fleming, p. 431. 
Shell sLibovate, rather convex, oblique ; anterior side pro- 
duced ; posterior side rather straight, and subtruncated below ; 
with a flexure, emanating from the umbo, and terminating on 
the margin; umbones small, nearly central, and slightly in- 
flected, beneath them a lanceolate cavity or lunule, covered 
with transverse, nearly obsolete strise, and wrinkles; surface 
white, smooth, and glossy ; hinge with a double primary tooth 
in each valve, and a small tooth-like knob in the left valve, 
locking into a cavity for its reception in the opposite one ; in- 
side smooth, glossy, and white ; each valve provided with two 
large muscular impressions; margins rather thick, for the size 
of the shell. Length three-eighths of an inch; breadth half 
an inch. 
Found at Greenock, by Stewart Ker, Esq., and is in the 
cabinet of Lady Jardine. 
Genus 32 — Ligula — Montagu. 
Shell inequivalve, inequilateral, transversely elongated ; with 
a large, broad, strong, transverse, spoon-like tooth in each valve, 
projecting inwards, each furnished with a pit for the insertion of 
the cartilage ; right valve furnished with a pretty large, elevated, 
erect, compressed tooth, situated close below the beak, fitting 
into a hiatus for its reception, which reaches to the beak, in 
the opposite valve; and in some species a minute tooth; exter- 
nal surface with a very thin, membranaceous epidermis; two 
muscular impressions in each valve, situate very close to the 
extreme sides of the valves, the posterior ones double, and ex- 
tending to nearly the umbones ; pallial impression with a rather 
large, transverse sinus, situated posteriorly. 
1. Ligula pr^tenuis, pi. XLII, f. 1. 
Ligula prcBtenuis, First Ed., pi. 14, f. 1 ; Anatina prcete- 
nuis, Turton, Biv., p. 48, pi. 4, f. 4 ; Amphidesma prcetenue, 
Fleming, p. 432; Bontcea prcetenuis, Leach, MSS., p. 6; Mya 
prcetenuis, Montagu, p. 41, pi. 1, f. 2 ; Donovan, V, pi. 178. 
Shell oval, thin, very brittle, compressed, and semipellucid ; 
umbones nearly central, very small; beaks rather acute, and 
inflected ; posterior side rounded ; anterior side somewhat acu- 
minated, and obliquely subtruncated, at which extremity the 
valves are a little open ; surface cream-white, transversely 
wrinkled, with extremely fine, nearly obsolete, concentric strise, 
covered with an extremely thin, cream-coloured, somewhat 
pilous epidermis; hinge with a broad, horizontal, internally 
projecting, hollow tooth in each valve; inside white. Length 
about half an inch ; breadth somewhat more than an inch. 
This rare British shell has been found at Poole, and other 
places on the Dorsetshire coast ; the south coast of Devon ; 
Frith of Forth ; and Portmarnock, Ireland. 
Genus 33 — Tellimya. — Brown. 
Shell equivalve, inequilateral, suborbicular, or transversely 
elongated, close all round ; left valve destitute of cardinal teeth, 
but provided with a pretty large hiatus, and two projecting 
lateral teeth, each having a groove in its centre ; sometimes 
with one or two rather long teeth on the right side ; right valve 
with two recurved, prominent teeth, which occupy the vacant 
space below the umbo in the opposite valve ; muscular impres- 
sions large and distinct ; pallial impression entire. 
Section I. — Shells orbicular. 
1. Tellimya suborbicularis, pi. XLII, f. 14, 15. 
Tellimya suborbicularis, First Ed., pi. 14, f. 14, 15 ; Mya 
suborbicularis, Montagu, p. 39, pi. 26, f. 6; Maton and Rackett, 
VIII, p. 41 ; Kellia suborbicularis, Turton, Biv., p. 57j pi. 
11, f. 5, 6; Fleming, p. 430; Forbes, p. 49; Bomia injiata, 
Phillipi. 
Shell suborbicular, very convex, thin, subpellucid ; umbones 
obtuse, nearly central, slightly inflected ; sides almost equal, 
rounded ; basal margin nearly parallel ; surface of a yellowish- 
white colour; somewhat glossy, with faint concentric striae; 
hinge with a single tooth in one valve, immediately under the 
beak, locking into a double incurved one in the opposite valve, 
with a somewhat laminated tooth behind the umbo in each 
valve ; inside glossy, white. Length three-eighths of an inch ; 
breadth half an inch. 
Some specimens exhibit a fine pearlaceous lustre, when de- 
prived of the epidermis. 
Inhabits the Frith of Forth, Plymouth, Salcomb Bay, and 
coasts of the Isle of Man. It is a borer, and penetrates the 
hardest limestone ; Forbes found it in the cavities of dead 
bivalves. 
2. Tellimya lactea, pi. XLII, f. 10, 11. 
Tellimya lactea. First Ed., pi. 14, f. 10, 11 ; Brown, Conch. 
Text Book, p. 138, pi. 17, f. 14. 
Shell nearly orbicular, inflated, thin, pellucid, and glossy 
white ; one valve with two teeth, locking into a triangular void 
in the opposite valve, with transverse laminae on each side ; left 
valve with a single, recurved, cardinal tooth, and a central, tri- 
angular, lamellated tooth ; and one remote, lateral tooth only. 
About a quarter of an inch in diameter. 
Found on the Devonshire coast, by Dr. Leach. 
3. Tellimya tenuis, pi. XLII, f. 12, 13. 
Tellimya tenuis, First Ed., pi. 14, f. 12, 13. 
Shell orbicular, smooth, glossy, snow-white, with fine, irregu- 
lar, concentric strise, much inflated ; umbones rather produced, 
and much turned to one side ; left valve destitute of cardinal 
teeth, but provided with two large lateral teeth ; right valve 
with two incurved, cardinal teeth, and a lateral one; inside 
white, and when viewed through a strong lens, has a shagreen- 
like appearance. Diameter three-eighths of an inch. 
Found at Newbigging, Northumberland, by W. C. Trevelyan, 
Esq., and is in the cabinet at Wallington. 
Section II. — Shells transversely ovate. 
4. Tellimya elliptica, pi. XLII, f. 16, 17. 
Tellimya elliptica. First Ed., pi. 14, f. 16, 17 ; Mya ferrugi- 
nosa, Montagu, Sup., p. 22 and 166, pi. 26, f . 2 ; Montacuta 
ferruginosa, Turton, Biv., p. 60. 
Shell transversely subovate, moderately convex, white, with 
obsolete, concentric wrinkles, and sometimes blotched with rust- 
coloured spots; umbones obtuse, situate nearest one side; basal 
margin nearly parallel ; hinge with two projecting teeth, one of 
which is erect, the other slopes inwards and downwards, these 
