Parti. PHILIPPINE LAND SHELLS — BARTSCH. 33 



AMPHIDROMUS MINDOROENSIS, new species. 



Plate 15, figs. 4, 5. 



Shell inflated, ovate. The first whorl and a half white, the rest 

 canary yellow excepting a very narrow band at the summit and the 

 peristome, which are white. The whorls are inflated, well rounded, 

 appressed at the summit, and marked by very retractive lines of 

 growth and exceedingly fine spiral striations. Aperture rather 

 large, oval ; outer lip thick, somewhat expanded and reflected ; inner 

 lip twisted, expanded at the base; parietal wall covered with a thin 

 callus. The inside of the aperture is colored like the exterior. 



The type (Cat. No. 245564, U.S.N.M.) was collected by Mr. Weber, 

 of the Philippine Bureau of Sciences, in Mindoro. It has six whorls 

 and measures — length, 53.2 mm. ; diameter, 29.2 mm. 



GROUP OF AMPHIDROMUS QUADRASI. 



I am quite perplexed by the following species and feel at a loss 

 as to the treatment that should be accorded to it. My own collecting 

 in the Philippines has taught me that specific locality data are abso- 

 lutely necessary. Many forms, having a somewhat extended distri- 

 bution, break up into distinct and easily recognizable races on the 

 various islands. Not only is this true, but they may even become 

 differentiated into several forms in one island; for example, Cochlo- 

 styla ovoidea on Masbate. In Cataingan Bay we find an extremely 

 large, light-colored form on the hillsides of the west shore, while 

 across the bay on Dumurug Point, in the somewhat swampy low- 

 lands, we find a much smaller race which is always darker colored, 

 while at the town of Masbate we find a third equally distinct race. 



The perfectly uniform development at each place of these three 

 lots of mollusks would incline one to consider them as three distinct 

 species. It is only when one has made collections over the entire 

 range of Cochlostyla ovoidea and has obtained good series of speci- 

 mens from each locality that one sees that these races can be arranged 

 in such a way as to show complete gradation from one extreme to 

 another. 



The old collections made in the Philippines consisted chiefly of 

 purchased material collected by natives, frequently in widely sepa- 

 rate localities, dumped together without any data regarding its 

 source. This material has furnished little aid to the student of 

 geographic distribution. It is a stumbling block and the workers 

 who have amused themselves by describing unicolor, unicincta, oi- 

 cincta, tricincta, and quadricincta of certain species would have 

 saved time and trouble for their successors if they had chosen a 

 different field for amusement, because these forms occur in varying 

 numbers in a single brood of one parent. 



101825°— Bull. 100—17 3 



