PLECTOPYLIS. 145 



retractor of the penis is attached to the uterus wall (as in Hyalo- 

 sagda) instead of to the lung floor. 



The apex of the sheil is rather large, as in Gorilla, and usually 

 somewhat rugose. The grouping of the species is based upon the 

 form of the internal barrier, which is sometimes simple (pi. 40, fig. 

 4), sometimes excessively complex by the duplication of the parietal 

 and palatal barrier (pi. 40, figs. 7, 8, 12). Godwin-Austen found 

 shells with insects fixed between the teeth, so that there can be little 

 doubt that this barrier has been evolved for the protection of the 

 snail from predatory insects which swarm in the regions these forms 

 inhabit. 



P. achatina and cyclaspis are found on limestone hills, the animal 

 being shy, usually living in crevices and holes, and closely adhering 

 to the rock, even when moving about. 



This genus inhabits India and Farther India, extending north to 

 central China and south to Ceylon and the Philippine Islands. 



Subdivisions. 



Plectopy/is is herein expanded to contain two Chinese groups of 

 uncertain affinities, besides the typical group. 



Subgenus PLECTOPYLIS. Whorls regular, the last not distorted 

 nor grooved outside; having internal transverse barriers within the 

 last whorl. 



Subgenus TRATJMATOPHORA. Latter part of last whorl contracted 

 outside; throat obstructed by entering palatal lamella?, but having 

 no internal processes on the parietal wall. 



Subgenus STEGODEKA. Shell sinistral, the last whorl distorted 

 straightened, embracing the preceding ; aperture crescentic, tooth- 

 less ; throat very narrow, but without internal teeth or lamellae. 



Subgenus PLECTOPYLIS Bens. 



(Parietal vertical lamina double or compound^). 



P. achatina Gray, iii, 165. P. refuga Gld., iii, 164. 



trepercussa Gld. P. dextrorsa G.-Aust., iii, 164. 



P. anguina Gld., iii, 165. P. leiophis Bens., iii, 163. 



P. brahma G.-Aust. iii, 164. P. shiroensis G.-Aust., iii, 163. 



P. cyclaspis Bens., iii, 164. P. feddeni Blanf., iii, 163. 



catinus Bens. olim. P. brachyplecta Bens., iii, 103. 



P. karenorum Blanf., iii, 164. P. biforis Hde., iii, 166. 



P. revohita Pfr., Mon., v, 416. P. ponsonbyi G. A. 

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