THE AXLAIAL LIFE OF THE GROUP. 437 



the result that he soon published a considerable amount of valuable data 

 based on Hawaiian land shells, the object of which was to show that isolation, 

 segregation and variation were exceedingly important and until then almost 

 neglected factors in the theories advanced in efforts to explain tlic formation 

 of natural species. 



In the study of so small and apparently unimportant a subject as a land 

 snail, Dr. Gulick's philosophic mind found abundant material for the elucida- 

 tion of such profound subjects as the variation of species as related to their 

 geographical distribution illustrated by the Achafliitilidce (1872) ; diversity of 

 evolution under one set of external conditions; divergent evolution through 

 cumulative segregation ; intensive segregation ; divergent evolution and the 

 Darwinian theory; the inconsistencies of utilitarianism as the exclusive theory 

 of evolution, and lastly the preservation and acciunulation of cross-infertility 

 (1890-97). All of these were contributions to knowledge of the most far- 

 reaching significance. 



Import.^nt P^amilieh Represented. 



Scarcely less in numerical importance when compared with the genus 

 Achatinella are the one hundred and fifteen or more species of the genus 

 Amastra, representatives of which are distributed over all the large islands 

 of the group. The Lcptachatina, with an equally extended list of species. Is 

 likewise distributed ; and so the enumeration coidd be extended, but it is not 

 the intention in this place to attempt more than to encourage the beginner to 

 enter this fascinating field of study, where so much has already been accom- 

 plished and where yet so much remains to be done before this remarkably rich 

 and varied fauna will lie completely understood. 



In the gathering of these "jewels of the forest" the collector will find 

 many forms occupying a great variety of habitats, so that bushes, grass, trees 

 (including their leaves, trunks and limbs), the ground, dead leaves, the rocks 

 in the streams, the streams themselves — in short, almost every conceivable 

 place, but particularly the moist regions of the mountains — is liable to have its 

 shell inhabitant. The great majority of those species found on the ground, 

 however, are more liable to belong to some of the fourteen families other than 

 the AcliafiiK llidd , hut they will not be found entirely devoid of interest for 



Description of Plate. 



1, 2, 3. Chinese Snail (Fiviparus chinensis). 4, 5. Melania (Melania mauieiisis). 6, 7. 

 Melania mauiensis (Badly eroded). 8, 9, 10, 11. Melania neiecomhii. 12. Neritina vesper- 

 Una. 13. Neritina cariosa. 14. Pipipi {Nerita picea) on rocks at low tide. 15. Opercu- 

 lum from Tiviparus cliinensis. 16. Limniea (Limnrea oalmensis). 17. Shrimp [Opae] (Ma- 

 crobracMum grandimanxis) . 18. Dragon Fly [Pinau] nymph (Introduced). 19. Brackish 

 water Crab {Metograpsus messor). 20. Native Dragon Fly [Pinau] nymph. 21. Shrimp 

 (Macroirachium grandimanus) . 22. Water Beetles (Hydrobitis semicylindricus) . 23. Lim- 

 naea (L%mncea iinominis) . 24. Fresh water Clam (Spliarium sp.). 25. Water Beetles 

 (Bhanthns jmcificiis). 26. Sow-bug {PorreUio sraber). 27. Watcrboatman (Arctororisa 

 bhiHhiirni). 



