MOLLUSCA. 
117 
Tubicolaria.] 
Shell thin, brittle, subopaque, transversely subovate, and 
wedge-shaped when the valves are united; broad and widely 
gaping at the anterior side, from whence it gradually decreases 
until it reaches the opposite extremity, where the valves are 
closely shut; anterior termination of the valves with a small 
but prominent, terminal beak ; external surface covered with a 
brown or blackish-brown coating, irregularly wrinkled trans- 
versely; umbones rather prominent, and obtuse, situate near 
the larger side, at the junction of the valves on the superior 
margin ; hinge with an obscure, laminar, transverse tooth in 
both valves. General length half an inch ; breadth an inch. 
Turton mentions a variety of about half the ordinary size, 
but not differing in other characters, which is found buried in 
the back of old oyster shells. 
Inhabits rocks and stones at Torbay, and is an extremely 
local species. 
Genus 50. — Xylophaga. — Sowerby. 
Shell nearly orbicular, equivalve, inequilateral, gaping in 
front, the opening with an angular termination at the back; 
two small, somewhat triangular, calyxformed, accessory valves 
placed over the anterior side of the hinge, and a small tooth 
lying close to the umbo within each valve, besides an internal 
rib running from the beak to the basal margin, with a corres- 
ponding external depression ; anterior muscular impression 
smallest, situate on the superior margin, close to the beak ; 
posterior muscular impression large and obovate. 
1. Xylophaga dorsalis, pi. L, f. 8, 9j 10. 
Xylophaga dorsalis, Turton, Biv., p. 16 and 253, pi. 2, f. 4, 
5 ; Fleming, p. 455 ; Teredo dorsalis, Turton, Conch. Diet., p. 
185. 
Shell with rounded valves, but destitute of auricles, poste- 
riorly closed, and provided with an internal rib ; without a 
reflected, auriform process posteriorly ; the termination plain, 
and rounded; one valve furnished with a raised, curved process, 
and a small, slightly cleft one in the other; inside with a joint- 
ed, longitudinal rib, corresponding to the external groove. 
Found in a piece of wood, at Torbay, by Dr. Turton. 
Genus 51. — Dentalium. — Linnajus. 
Shell tubular, open at both ends, arcuated, increasing in dia- 
meter towards the anterior extremity, where the aperture is 
large and round ; opening of the pointed end very small, and 
with a lateral fissure in some species ; external surface ribbed, 
striated, or smooth, but never with annulations. 
1. Dentalium entalis, pi. LVI, f. 7. 
Dentalium entalis. First Ed., pi. 1, f. 7 ; Pennant, IV, p. 
145, pi. 90, f. 154; Montagu, p. 494; Donovan, pi. 48; Brown, 
Conch. Text Book, p. 52, pi. 9» f. 33. 
Tube slightly arcuated, tapering, smooth, and glossy; fre- 
quently with inequidistant, circular, irregular wrinkles, or lines 
of growth ; of a yellowish-white colour. Length an inch and a 
half; diameter at larger end two-tenths of an inch, smaller end 
about a twentieth of an inch. 
Inhabits many of the British and Irish coasts. 
2. Dentalium dentalis, pi. LVI, f. 8. 
Dentalium dentalis. First Ed., pi. 1, f. 8; Linnaeus, Syst. 
Nat., p. 1263, No. 785; Maton and Rackett, p. 237; Montagu, 
p. 495. 
Tube slender, subarcuated, very taper, terminating in a small 
point; surface with regular, close-set, longitudinad striae; some- 
times a few annulations can be traced at the wider end ; colour 
white, but not glossy. Length half an inch ; diameter at the 
base half a line. 
Discovered by Colonel Montagu, at Falmouth and south 
coast of Devonshire, and is a very local species. 
3. Dentalium octangulatum, pi. LVI, f. 2. 
Dentalium striatum, First Ed., pi. 1, f. 2; Dentalium octan- 
gulatum, Donovan, V, pi. 162 ; Dentalium striatulum, Maton 
and Rackett, p. 238; Montagu, Sup., p. 155. 
Tube strong, white, arcuated, tapering to a very fine point, 
and furnished with eight strong, longitudinal ribs, which give 
to the base, or wider end, an eight -sided appearance ; the 
nterstices between the ribs are tristriated. Length about two 
inches. 
A local species, found on the sands at Lelant, Cornwall ; I 
met with a single specimen at Holy Island. 
4. Dentalium labiatum, pi. LVI, f. 4, 5. 
Dentalium labiatum. First Ed., pi. 1, f. 4, 5. 
Tube strong, smooth, white, subarcuated, and truncated at 
the smaller end ; apex closed by a perforated, testaceous lid. 
I found several specimens of this shell in Lough Strangford, 
Ireland. They are now in the cabinet of Lady Jardine. 
5. Dentalium Gadus, pi. LVI, f. 1. 
Dentalium Gadus, First Ed., pi. 1, f . 1 ; Montagu, p. 496, 
pi. 14, f. 7 ; Maton and Rackett, p. 238. 
Tube subpellucid, glossy, snow-white, considerably arcuated; 
contracted towards the larger end, and tapering to a very small 
point at the other extremity. Length about three-eighths o 
an inch ; diameter about one-sixteenth. 
Inhabits the British Channel, but is a very rare species. 
