235 



Genus 8. HELIX, Linnceus. 



Animal ; similar to that of Bulimus. 



Shell ; globose or orbicularly depressed, mostly smooth, generally 



covered with an epidermis ; spire rather obtuse, but little raised ; 



aperture transverse ; lip mostly reflected. 



Little can be said of this genus that has not been said already in speak- 

 ing of Bulimus. The animal is the same. The form of shell which it 

 includes, namely, all that are globose or orbicularly depressed, embraces 

 about twice as many species in number, but a much larger proportion that 

 are small. Dr. PfeifFer enumerates 1,674 species, including thirty-one of 

 the type Streptaxis and four of Tomigerus, and some additions have since 

 been made to this number in the Proceedings of the Zoological Society. 

 But his list comprises many that have not been verified by observation, 

 and I shall therefore content myself by quoting the 1,500 species which I 

 have examined, described, and figured in the f Conchologia Tconica.' 



The remarks on the geographical distribution of the Bulimi apply very 

 generally to the Helices, except that they have a more extended range to 

 the north. The proportion of Helices to Bulimi in the United States and 

 adjacent territories of North America is as 79 to 11, while in the particular 

 State of Massachusetts, whose isothermal parallel of temperature is that of 

 Scotland, there are sixteen Helices and no Bulimus but the B. lubricus, 

 which is an abnormal form of the genus, separated, with reason, by British 

 authors under the name of Zua. 



1. abjecta, Lowe. 



2. abnormis, Pfr. 



3. acies, Parts. 



4. actinophora, Lowe. 



5. acuducta, Bei/s. 



6. aculeata, Mull. 



7. acuminata, Pfr. 



8. acuta, Lam. 



9. acutimargo, Pfr. 



10. Adansoni, Webb. 



11. adusta, Soto. 



12. adusta, Hinds. 



13. ad vena, Webb. 



14. aegrotus, Reeve. 



15. eemula, Rossm. 



16. senea, Krauss. 



Species. 



17. aeruginosa, Pfr. 



18. afficta, Per. 



19. Af'ricana, Pfr. 



20. Aglaja, id. 



21. agreabilis, Zieg. 



22. alabastrites, Mich. 



23. alauda, Per. 



24. Albaiensis, Sow. 



25. Albanica, Zirg. 



26. Albersi, Pfr. 



27. albicans, id. 



28. albidens, Bens. 



29. albolabris, Say. 



30. Alexandri, Gray. 



31. algira, Linn. 



32. alliaria, Mill. 



33. alligans, Adams. 



34. Alonensis, Per. 



35. alpina, Bign. 



36. alternata, Say. 



37. alveus, Adams. 



38. Amazonica, Pfr. 



39. anibigua, Adams. 



40. amicta, Reeve. 



41. ammoniformis, J)' Orb. 



42. Ammonitoides, Reeve. 



43. ammonoceras, Pfr. 



44. ampulla, Bens. 



45. ampullarioides, Reeve. 



46. anaglyptica, id. 



47. anceps, Gould. 



48. Andicola, Pfr. 



2h2 



