THE COOK'S OE HARVEY ISLANDS. 411 



Out of nineteen species found on Mangaia, one only is confined to that island. 

 The Partula, which does not occur on the other islands of the group, is common 

 to Tahiti and the Austral Islands. All the twelve species were collected in two 

 small portions of the island. 



As stated in the commencement of this article three of the islands are virgin 

 ground to the shell-collector. 



Of the fifty-four known species, thirty are peculiar to the group, and twenty- 

 four are more or less widely diffused throughout the other Polynesian Islands. 



