128 



MOLLUSCA. 



Genus 18. — Lacuna. — Turton. 



Shell thin, subglobose, or ovatcly subcorneal ; 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. Phasiandla vinctus, 

 p. 9. 



4. Lacuna quadrifasciata, pi. XIII, f. 35. Turbo qua- 

 drifasciatus, p. 16. 



5. Lacuna bifasciata, pi. XIII, f. 44, 45. Phasiandla 

 bifasciata, 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. LVN, f. 8. 



Helix lacuna, Montagu, p. 428, pi. 13, f. 6; Maton and 

 Rackett, 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 petr,ea, 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 ziczac, pi. X, f. 26, 27. Turbo ^ic~ac, 

 p. 16. 



10. Littorina neritiforma, pi. X, f. 24. Turbo neriti- 

 Jbrmis, 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. 



