COCHLOSTYLA OF MINDORO PROVINCE 455 



certain stretch of coast line Cerion tridentata Pilsbry and Vanatta occurs 

 and at the east end for a mile or more Cerion peracuta Torre. Here 

 the same story of mutation applies, and I know a number of additional 

 mutating colonies of Cerions in the Bahamas and Cuba. It is also true 

 of Vivipara in Lake Lanao, Mindanao, Philippine Islands, and of at 

 least four species of marine mollusks of the family Pyramidellidae in 

 United States waters, as well as of the mollusks here under discussion. 



Cochlostyla (Prochilus) virgata (Jay), as our sjmonymy shows, has 

 been rechristened many times, and it is not surprising that this should 

 have been the case. Isolated specimens reaching museum men un- 

 aware of the mutating condition of this complex would, on account of 

 the great difference they displayed when compared with allied described 

 species, be subjected to naming. It is only when a mass of material, 

 such as lies before me, has been assembled or when in the field one finds 

 that these mutants are produced in a single laying of a parent that their 

 true inwardness becomes revealed. There is now no more excuse for 

 holding them distinct species than there would be justification to give 

 specific rank to all the horticultural varieties of chrysanthemums and 

 dahlias displayed annually in our flower exhibits. 



What the progenitors of Cochlostyla (Prochilus) virgata (Jay) may 

 have been is a vital question, but opinions expressed at the present 

 must be looked upon as mere conjectures. The recurrence of certain 

 elements suggests an affinity with Cochlostyla (Prochilus) cuyoensis 

 (Pfeiffer), whose races are found on the islands to the south and south- 

 east of Mindoro. Certain other features, such as hydrophanous fi- 

 gurations of the periostracum, as well as the general coloration, suggest 

 some members of the Cochlostyla (Chrysallis) aspersa mindoroensis 

 (Broderip) complex, while still others suggest the small, plain yellow, 

 thick-shelled Cochlostyla (Prochilus) cerina Bartsch, which appears 

 to be common in southeastern Mindoro. It is possible that this has 

 contributed the yellow element in our mutating complex. 



An examination of the soft anatomy of these creatures, which I hope 

 shortly to be able to make through the kindness of Mr. de Mesa, may 

 throw additional light upon our problem. 



cochlostyla (prochilus) virgata (jay) 



Plates 102-105 



1839. Bulimus virgatus Jay, Catalogue of recent shells in the cabinet of John C. 

 Jay, p. 120, pi. 6, fig. 4. 



1839. Bulimus porraceus Jay, ibid., p. 120, pi. 6, fig. 5. 



1840. Bulimus labrella Grateloup, Actes Soc. Linn. Bordeaux, vol. 11, p. 165. 



1840. Partula labrella Grateloup, ibid., pp. 423-424, pi. 4, fig. 6. 



1841. Bulinus dry as Broderip, Proc. Zool. Soc. London, 1840, pp. 94-95. 



1841. Bulinus sylvanus Broderip, ibid., p. 95. 



1842. Bulinus virgatus Sowerby, The conchological illustrations, p. 8, p. 1S6, 



figs. 112-114. 



