128 
MOLLUSCA. 
Genus 18. — Lacuna. — Turton. 
Shell thin, subglobose, or ovately subconical; spire short, 
sometimes very short, with a somewhat obtuse apex ; volutions 
somewhat tumid; aperture subrotund, or subovate; outer lip 
thin, never reflected, and incomplete posteriorly ; columella 
usually broad, and depressed, with an elongated, narrow umbili- 
cus behind it ; whole outer surface covered with a very thin, 
horny epidermis. 
1. Lacuna retusa, pi. X, f. 52, 53. 
Lutea lacuna, First Ed., pi. 46, f. 52, 53. 
Shell very thin, subglobose, hyaline, and of a greenish-brown 
colour ; spire extremely small, hardly elevated above the body, 
and consisting of two volutions ; body with a subcarinated zone 
in the centre ; aperture obliquely ovate ; outer lip thin, and 
sharp at the edge ; pillar lip narrowly reflected, with a slight 
slit behind. 
Found at Dunbar, by General Bingham. 
2. Lacuna pallidula, pi. XIII, f. 17> 19- Natica palli- 
dula, p. 25. 
3. Lacuna vincta, pi. XIII, f. 46. Phasianella vinctus, 
p. 9. 
4. Lacuna quadrifasciata, pi. XIII, f. 35. Turbo qua- 
drifasciatus, p. 16. 
5. Lacuna bifasciata, pi. XIII, f. 44, 45. Phasianella 
hifasciata, p. 10. 
6. Lacuna cornea, pi. XIII, f. 47. Phasianella cornea, 
p. 10. 
7. Lacuna canalis, pi. XIII, f. 48. Phasianella canalis, 
p. 9. 
8. Lacuna fasciata, pi. XIII, f. 54. Phasianella fas- 
ciata, p. 10. 
9. Lacuna Montagui, pi. LVII, f. 8. 
Helix lacuna, Montagu, p. 428, pi. 13, f. 6; Maton and 
llackett, p. 201. 
Shell thin, smooth, pellucid, subglobose, of a light horn- 
colour ; body large, tumid ; spire small, consisting of three 
depressed volutions, the apicial one very small, and placed 
somewhat laterally ; aperture large, suboval ; outer lip very 
thin ; pillar lip reflected, and white ; with a groove-like canal, 
which terminates in a small, but deep umbilicus. Length a 
quarter of an inch ; breadth nearly the same. 
Montagu, — on whose authority we give this shell, — says, “ it 
must not be confounded with Lacuna pallidula, whose pillar 
lip is somewhat of the same form, but much broader; the smal- 
ler volutions more lateral, and more compressed; the body and 
mouth also are greatly larger.” 
Found on the Devonshire coast, and on the shore near 
Southampton. 
Genus 21. — Margarita Leach. 
Shell trochiform, depressed ; volutions few, well defined by 
the suture; base of body subdepressed, and provided with a 
large umbilicus ; aperture nearly circular, and covered by a 
horny operculum, consisting of few volutions. 
1. Margarita aurea, pi. X, f. 23. Turbo aureus, p. 17. 
2. Margarita carnea, pi. X, f. 36, 37. Turbo carneus, 
p. 17. 
3. Margarita margaritacea, pi. X, f. 28, 29. Turbo 
margarita, p. 17. 
4. Margarita olivacea, pi. X, f. 30, 31. Turbo olivacea, 
p. 17. 
Genus 22. — Littorina. — Ferussac. 
Shell turbinated, generally ovate, or oblong-ovate, for the 
most part thick and solid; spire acuminated and subturreted 
in some species ; very short and obtuse at the apex in others ; 
aperture entire, round, or slightly elliptical, sometimes a little 
acute obove ; outer lip sharp-edged, thickened within ; colu- 
mella somewhat flattened ; operculum spiral, horny, and elastic, 
consisting of a few rapidly enlarging volutions, and furnished 
with a central nucleus. 
This genus to be substituted for that of Turbo, page 15; it 
also comprehends the genus Neritoides, p. 25, and consists of 
the following species, namely, 
1. Littorina littorea, pi. X, f. 1, 2, 3, 4, 5, 6, 7? 8, 9. 
Turbo littoreus, p. 15. 
2. Littorina rudis, pi. X, f. 10, 11, 12, 13, 14, and 25. 
Turbo rudis, p. 15. 
3. Littorina jugosa, pi. X, f. 15, 16. Turbo jugosus, 
p. 16. 
4. Littorina tenebrosa, pi. X, f. 18, 19. Turbo tene- 
brosus, p. 16. 
5. Littorina PETRiEA, pi. X, f. 17. Turbo petrceus, 
p. 16. 
6. Littorina labiata, pi. X, f. 20, 21. Turbo labiata, 
p. 16. 
7. Littorina ventricosa. Turbo ventricosus, p. 16. 
8. Littorina dispar, pi. X, f. 22. Turbo dispar, p. 16. 
9. Littorina zigzag, pi. X, f. 26, 27. Turbo ziczac, 
p. 16. 
10. Littorina neritiforma, pi. X, f. 24. Turbo neriti- 
formis, p. 17. 
11. Littorina fabalis, pi. X, f. 38, 39. Turbo fabalis, 
p. 17. 
12. Littorina striatula, pi. X, f. 33, 34. Turbo stria- 
tulus, p. 17. 
13. Littorina neritoides, pi. XIII, f. 14, 15, 21, 22. 
Neritoides littoralis, p. 25. 
14. Littorina sexatilis, pi. LVII, f. 21, 22. 
Littorina sexatilis, Johnston, Trans. Berwick. Nat. Hist. 
Club, III, p. 268 ; Macgillivray, Moll. Ab., p. 138 ; Turbo sex- 
atilis, Bean, MSS. 
Shell moderately thick, subglobose, slightly conical ; length 
and diameter nearly equal ; spire about a third of the length, 
consisting of three spirally striated volutions, divided by a deep, 
well defined suture; body somewhat flattened above, and a little 
angular below ; aperture ample, nearly orbicular, and deep cho- 
colate-brown within ; outer lip thin, and united to the body in 
an angular form ; inner lip narrowly reflected on the columella, 
and provided with a slight callosity, and is of a brownish-purple 
colour; external surface varying in colour, being white, yellow, 
or cinereous, tesselated with dull brown or olive. Length and 
diameter upwards of a quarter of an inch. 
Found on the Yorkshire coast, by Mr. Bean, of Scarborough; 
and Professor Macgillivray gives as localities the Aberdeenshire 
and Kincardine coasts. 
