24 THE NAUTILUS. 



effect of conditions in the environment, not only on vegetable but on 

 all other forms of life as the application of moisture to the warm dry 

 soil, and I may add right here, that in my opinion the proportions 

 of heat and moisture, especially in the early stages of growth of an 

 organism, is probably the most fruitful source of variation. 



The -rains of Southern California appear to be brewed in the 

 south, at least they are brought here on the wings of the south wind. 

 When the rains are excessive, the gulches, creeks and canyons on 

 these islands become raging torrents ; the thin soil in many places, 

 and especially on the south slopes which receive the full force of the 

 storms, becomes filled with water to the bedrock ; then landslides 

 more or less extensive occur, when rock, land and cactus are launched 

 into the raging waters and carried out to sea. 



With these destructive occurrences whole colonies of snails are 

 frequently carried away and destroyed, except occasionally a few 

 fortunate individuals that may become stranded with other debri» 

 lower down on the sides of the creek or canyon, where if the con- 

 ditions are favorable a new colony will spring up with such modifica- 

 tiont of the creature and the shell as the combination of the already 

 organized creature and the new conditions in the environment de- 

 termine. 



(To be Continued.) 



PUBLICATIONS EECEIVED. 



The Fossil Land Shells of Bermuda. By Addison Gulick 

 (Proc. Acad. Nat. Sci., Phila., 1904, pp. 406-425, plate 36). The 

 shells collected by the author from quarries of the seolian limestone 

 of Bermuda are described and discussed in this valuable paper. Of 

 17 species of land snails found fossil, 14 are probably peculiar to 

 Bermuda. The recent fauna contains 13 indigenous species, 6 of 

 them peculiar to the island. The most notable of the fossils discov- 

 ered by Mr. Gulick are new species of Poecilozonites, Euconulus, 

 Zo?iitoides, Vertigo (2 species), Carychium and a Strobilops referred 

 to hubbardi. " Dr. Pilsbry's conclusion, from the anatomy of Poecil- 

 ozonites, that the oldest importations to Bermuda came from contin- 

 ental America, is thus confirmed by a large majority of the fossil 

 forms." Some of the commonest species in the modern fauna are 

 wanting in the fossil deposits, such as Polygyra microdonta and Heli- 

 cina convexa. Mr. Gulick give3 an interesting discussion of the con- 

 dition of the island at the time the extinct forms flourished, too long 

 for abstract here — H. A. P. 



