HABITS AND STATIONS. XXXV 



like, and it takes some experience to find them. The eye 

 must be trained. I have had good collectors follow me ami 

 say that the best collecting was on the trees I had looked over ! 



I have never seen an Achatinella crawling on the ground, 

 though occasionally on returning over a trail, one finds shells 

 which had been dislodged some time before. Mr. Spalding 

 tells me that his experience is the same. See also pp. 99-102 

 for observations by Mr. Henshaw. These snails are certainly 

 more inert than our American Helices, which if dropped usu- 

 ally make off promptly ; yet it seems likely that by night they 

 wake up. It seemed to me that the young shells wandered 

 more widely than the adults. Certainly with us young snails 

 walk more in the day time and wander more than old ones. 

 In the head of Kamalo, Molokai, there was a forest of native 

 trees, now all dead and prostrate, doubtless from the destruc- 

 tion of the undergrowth by cattle or deer. It is now covered 

 with low lantana, standing in patches, groups or singly, and 

 bearing a copious population of Partulina redfieldi kama- 

 loensis. They are also on the dead trees. It does not seem 

 likely that they could have spread so universally from the 

 trees to the immigrant lantana without crawling on the 

 ground for short distances. Observations with a lantern 

 should be made in some such prolific colony. However this 

 may be, it is evident that migration is slow, and probably 

 for the greater part by way of the interlocking branches of 

 adjacent trees. Where the vegetation is dense, there is often 

 a pretty continuous highway; but the colonies of shells on 

 isolated trees or small groups of shrubs must often be segre- 

 gated from their fellows for many generations. 



Mr. Perkins has mentioned a fact which I find is known to 

 all Island collectors, that a species may be found on one tree 

 or shrub, year after year, without spreading to neighboring 

 shrubs. This is true also of some arboreal Pupillidcc and 

 Endodontidce. It strikes the outsider as uncanny to be taken 

 to one certain tree to collect specimens of some snail which 

 either has never been found anywhere else, or nowhere else 

 in the neighborhood or district. To find that trees just as 

 good all around are barren of specimens is always a surprise. 



