MOLLl'SCA. fi27 



file body iiparly its wliolo length, and serving for progressive motion.— 

 This order confaius thirty-tlirei' genera : 



1. Vitrina; 2. Testacella; 3. Umax; 4. rarmacella ; 5. Ocliidium ; 6 Do- 

 labella; 7. Laplysia; 8. Bulla; 9. Retusa; 10. Akera ; II. Diaphana ; 12. 

 BuUaea; 13. Accra; II. Ancylus ; 15. Crepidula; 16. Calyptraea; 17. Pile- 

 opsis; 18. Fissurella; 19. Sipho ; 20. Emarginiila; 21. Parraophorus; 22. 

 Umbrella; 23. Pleiirobrandms; 2i. Patella; 25. Chiton; 20. Chitonellus ; 

 27. Phyllidia; 28. Doris; 29. Tethys; 30. Scyllaja; 31. Tritonia; 32. Eolis; 

 33. Glaiicus.— Of which we have tii<ured the follovviug species : 



Vitrina pellucida.—T\\e Pellucid Vitrina. Plate Ixxv. fig. 5. Extremely 

 thin, pellucid, and glossy; depressed, with the spire very short; of a pale 

 yellowish.green ; aperture large and oval. Fourteen inches long. Inhabits 

 dry places of Europe. 



Testacella ILiliotidea.— The Haliotis-Sb.aped Testacella. Plate Ixxv. fig. 

 23. Shell oblong.ovate, auriform ; left margin slightly reflected ; exceedingly 

 thin, transparent, and yellowish. Inhabits the middle provinces of France. 



Limnx Kufiis.— The Red I>iniax. Plate Ixxv. fig. 29. Shell ovate-obloug 

 both margins reflected ; very thin, diaphanous, slightly wrinkled, and of a 

 pale straw-yellow colour- Inhabits gardens in Britain and France. 



Parmacella calycutula.—Thc Cup-Shaped Parmacella Plate Ixxv. fig-. 31. 

 Ovate ; left margin broad and reflected, right margin reflected at top and 

 acute beneath ; exceedingly thin, transparent, and of a pale yeUowisli- 

 brown. 



Bolohella Ru7nphii.—li\im^\\m%'s Dolobclla. Plate Ixxv. fig. 30. Base 

 thick, callous, and subspiral ; dilated above, thin, and wedge-shaped. Inha- 

 bits the Indian owan, at the Isle of France. 



Laplysia radiata.—ihe Radiated Laplysia. Plate Ixxvi. fig. 25. Nearly 

 round, left margin somewhat reflected; outer lip acute ; yellowish horn- 

 coloiu-ed, witli brown radiations; and two concentric bands. 



Bulla lignaria.— The Wood-like Bulla. Plate Ixxvi. fig. 25. Narrowed 

 towards the top, where it is slightly umbilicatcd ; yellowish-brown, with 

 numerous transverse pale striae. Two inches long. Inhabits the British 

 seas. 



Betitsa pUcuta.— The Plaited Retusa. Plate Ixxvi. fig. 27. White, opaque, 

 subcylindrical ; spire produced ; aperture elongated, straitened at top; two 

 traasverse plaits, and several oblique ones, at the base of the columella ; 

 outer lip thin, slightly inflected. One-third of an inch long. Inhabits the 

 sea at Dunbar. 



Akera flex-ilis.—Th<^ Flexible Akera. Pljte Ixxvi. fig. 29. Oval, membra- 

 naceous, flexible ; horn-coloured, with a convolute truncated channelled 

 spire. Three-fourths of an inch long. Inhabits the British seas. 



Diaphana Candida— Tha White Diaphana. Plate Ixxvi. fig. 30. Pure 

 white, ventricose ; aperture whole length of the shell, narrowed .at top ; 

 spire short ; subumbilicated. One-sixth of an inch long. Inhabits the Frith 

 of Forth. 



Bullcca aperta.—T\\G Open Bullaia. Plate Ixxvi. fig. 23. Suborbicular, 

 pellucid, white, faintly striated, and sli^htly wrinkled ; almost entirely 

 open. Half an inch long. Inhabits the Briiish seas. 



Anctjlus ohlonga.—The Oblong Ancylus. Plate Ixxvi. fig. IS. Aperture 

 elougated, vertex turned to one side ; with fine concentric striae ; pale horn- 



