COCHLOSTYLA OF MINDORO PROVINCE 379 



shape, or color, which, though they look distinct when viewed 

 separately, may be the offspring of one mother. 



I am deeply indebted to the Coast and Geodetic Survey of the 

 United States Department of Commerce for the splendid chart of 

 Mindoro and the adjacent islands, no. 10, from which I am reproduc- 

 ing as plate 117 the northwestern end, as plate 116 the northeastern 

 end, and as plate 118 the southern end; also as plate 119 the islands 

 stretching to the northwest of Mindoro and as plate 120 those to the 

 southeast of Mindoro. These plates show the territory where col- 

 lecting has been done and also call attention to the large part of the 

 interior, especially of the central portion of the island, still awaiting 

 exploration and from which we may look for many new things. 



A careful examination of these contour maps will reveal the greatly 

 diversified topography of this province. We have here mountaintop 

 after mountaintop rising to great elevations, Mount Halcon, its highest 

 peak, registering 8,865 feet. A subsidence of comparatively little 

 moment would split the region into many lesser islands, a fact that 

 accounts for its greatly diversified fauna. The factors of isolation 

 on these circumscribed areas over a long period have made possible 

 the adjustments of the chemical constituents of the germ cells, as well 

 as the adjustments of the organism as a whole, to the environmental 

 factors presented by the restricted habitat. 



Cochlostylas are tree snails that require a forest or tree habitat for 

 their existence, and they are as effectively limited in their wanderings 

 by the lowland cogon grass-covered areas as they would be if water 

 separated the areas occupied by them. 



Genus COCHLOSTYLA Ferussac 



In this extremely large genus, the shell presents an enormous range 

 of variation in form. It may be lenticular, helicoid, or bulimoid; 

 it may be nonumbilicate, rimate, or narrowly umbilicate; the outer 

 lip may be almost without reflection or it may be strongly expanded 

 and reflected. The columella may be simple, twisted, or toothed. 

 The surface of the shell is covered by a periostracum, which is usually 

 more or less hydrophanous and varies from a scarcely perceptible to 

 a heavy cuticle. The sculpture never attains the strength of ribs, 

 but the lines of growth in some species approach ribbing. Incised 

 spiral lines or fine striations are usually present. 



The shell of some species is unicolor, while others show axial bands 

 or fulgurations, and may have spiral color bands that may be confined 

 to the periostracum or may be part of the substance of the shell. 

 Many colors and tints are represented in the color scheme of the genus. 



Of the rest of the anatomy, Dr. Pilsbry states: 9 



« Man. Conch, ser. 2, vol. 9, pp. 216-217, 1895. 



