12 PROCEEDINGS OF THE ACADEMY OF [Jail.; 



the granulations continue out to the Hp ; sometimes they only appear 

 in the middle part of the last whorl and become obsolescent towards 

 the lip. They are well shown and their connection with the trans- 

 verse wrinkles is apparent in the figs. 22, 25, 26, Plate I. This 

 peripheral granulation is thus characteristic of certain of the speci- 

 mens taken at Orange Hill and Rose Alount, Montego Bay, and is 

 not found in the normal L. aureola from any other locality examined. 

 The forms possessing it might be designated by a varietal name, as 

 montegoensis, and it is probably the beginning of a new species, 

 or what would become one if the forms continued to live at the 

 Montego Bay localities, which, unless the settling up of the country 

 continues, is likely to be the case, they having survived the advance 

 of civilization for perhaps a century. But it may be a variation 

 not due directly to the aridity of the country produced by the 

 clearing of the land — not referable to change of environment alone — 

 but to hyhridity, and this might work out in future generations. 



We thus have two species, each developing a dwarfed race under 

 similar conditions of environment, but in which the causes for the 

 development of the new sculptural characters which accompany 

 the dwarfing are probably not referable to the same causes. 



The Variation in Size. 



The amount of the variation in size may be graphically shown 

 by plotting the dimensions of the forms to scale in the manner 

 adopted in a previous paper.^ These dimensions are given below. 



Variation in size in Lucidella granulosa C. B. Adams. — The 

 forms of this species compared in fig. 1 are from Somerset, Somerset 

 Road, Benmore, Kendal Road one mile north of Mandeville, and the 

 Sturridge place, three miles southeast of Mandeville. Those from 

 Somerset and Somerset Road are the largest, those from Kendal 

 Road and the Sturridge place the smallest. The Benmore specimens 

 lie between these two, but nearer to the larger group, so that the plot 

 shows two groups as to size, with a gap between the two that is 

 not entirely bridged over by the Benmore specimens. The normal 

 forms, represented by the group of larger specimens from these 

 localities, show some variation in the sculpture, but are in general 

 as described above for the forms from Somerset and Somerset Road, 

 with a nearly non-tuberculated periphery on the last whorl. Only 



* A. P. Brown, Variation in some Jamaican Species of Pleurodonte, Proc. 

 A. N. S. P., 1911, pp. 117-164 figs. 2-14. 



