THE COOK'S OR HAEVEY ISLANDS. 



409 



The only variation is in size, more or less elevated spire, and the color varies 

 from light to dark corneous, rarely with an obscure band on the last whorls. 



They can scarcely be distinguished from A. Californica, except in being lighter 

 colored, and the spire more planulate in outline. A. Vitiensis is larger, much 

 darker colored, and always banded, the spire more convex, and inhabits brackish- 

 water swamps. 



It is surprising that Mr. Pease, when he published his Monographs of Ompha- 

 lotropis and Assimmea, should have referred Mousson's parvula to the former genus. 

 And in his list of Polynesian land shells he commits a graver fault by including it 

 in both genera. 



RECAPITULATION. 



The following list and columns will exhibit, at a glance, the distribution of the 

 land shells over the four islands explored by me: — 



Aitutaki. Atiu. Mangaia. 



2. 





3. 





4. 





5. 





6. 





1. Microcystis excrescens, Mouss. 

 subcicercula, Mouss. 

 venosa, Pease 

 Discoidise, Oarr. 

 conula, Pease. 

 Samoensis, Mouss 



7. Patula tenuicostata, Qarr 



8. " canalis, Oarr. 

 Atiensis, Pease 

 proxima, Oarr. 

 rudis, Oarr. . 

 decorticata, Oarr. 

 HarveyensiSj Oarr. 

 Toungi, Oarr. 

 planospira, Oarr. 

 unilamellata, Oarr 



17. Pitys zebrina, Oarr. . 



18. " multilamellata, Oar 



19. " imperforata, Pease 



20. " rdtellina, Pease 



21. " Roratongensis, Pease 



22. Libera fratercula, Pease 



23. " cavernula, Oarr. 



24. " tumiiloides, Oarr. 



25. " sp. . 



26. Stenogyra Tuckeri, Pfr. 

 80 



9. 





10. 





11. 





12. 





13. 





14. 





15. 





16. 





Earotouga. 

 X 



X 



X 



X 



X 



X 



X 



X 



X 

 X 

 X 

 X 

 X 

 X 

 X 

 X 

 X 



X 

 X 

 X 



X 

 X 



X 

 X 



X 



X 



