THE ANIMAL LIFE OF THE GROUP. 435 



recent and most painstaking authdrities. the renowned Dr. H. A. Pilsbry, of the 

 Academy of Natural Sciences of Philadelphia, and the local speciali.st, Dr. C. 

 Montague Cooke, of the Bishop Museum. It is hoped that their conclusions 

 as published from time to time, since they are based on extensive field collec- 

 tions and the examination of the hundreds of thousands of shells now in 

 museum collections, will at least settle once and for all the c|uestion of "which 

 is which" in the shell fauna of these islands. 



But we cannot afford to pass without comment in this connection the 

 interesting investigation of my friend and colleague, Dr. Cooke, on the distri- 

 bution and variation of a single species '• of Achatinella from Nuuanu Valley, 

 published by the Bishop Museum. 



For his purpose he selected a shell from Nuuanu Valley that, as a recog- 

 nizable species, seemed to be fairy abundant and is commonly regarded as oc- 

 curring only in that single valley. The northwest side of the valley was care- 

 fully explored and about three thousand shells collected, over half of which 

 belonged without question to the single species under investigation. Begin- 

 ning at the upper end of the valley, at the famous Nuuanu Pali, the habitat 

 studied included the main ridge on the left and the sub-ridges and valleys that 

 extend into the main valley of Nuuanu from one hundred to three hundred 

 yards at almost right angles to the main ridge. On account of the sedentary 

 habits of the land snails, these ridges, owing to the deep valleys that separate 

 them one from another, form isolated habitats. Of the twenty-three sub- 

 ridges the upper seventeen were all found to offer a very uniform environ- 

 ment as far as food, moisture and elevation were concerned. All were 

 foiind to be inhabited by the particular species of land shell being studied. In 

 .some instances the sub-ridges were further sub-divided into special localites 

 so that the area of none of the localities was over one hundred and fifty yards 

 in diameter. Specimens were found to favor the more open localities between 

 one thousand and fourteen hundred feet elevation. 



With the data and material at hand Dr. Cooke was able to describe twenty- 

 five well-marked color varieties, all of which were more or less closely con- 

 nected by intermediate specimens. When we remember that the species in its 

 various forms is distributed over an area only a few hundred yards wide at 

 most, by two or three miles in length, it is clear that much scientific interest 

 must attach to such studies. Among many other interesting facts it was 

 found that the shells varied not only from one ridge to another, but from one 

 colony to another. In fact, the specimens secured from a given limited locality 

 often varied among themselves to a remarkable degree. 



It was the early appreciation and observation of facts such as these, and 

 a desire to find the law that underlies such facts, that led my friend, the dis- 

 tinguished evolutioni.st. Rev. John T. Gulick, in his early youth to begin a 

 systematic collection of land shells. Latei', through the in.spiration of Dar- 

 win's great book on "The Origin of Species.""" he set to work in earnest, with 



' Achntinelln muUUonuta. M'ublislli-d in 1859. 



