622 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 117 



and Peninsular Thailand probably have different proportionate 

 representation of color forms, there is no evidence that this is indica- 

 tive of subspecific differentiation. 



The specimens of atricallosus pattern from Tha Lo had the extent 

 of the parietal coloration noticably reduced and there is one lot of 

 four shells (ANSP 284220, CNHAl 109473) from "Khao Luang," a 

 mountain west of Prachuab Ku'ikhan^ at 11°40' on the Burmese- 

 Thailand border that are quite unusually patterned (pi. 1, fig. 2). 

 They have the callus and varbc of atricallosus, but a reddish-brown 

 color suffusion on the body whorl that is hitensified into vague radial 

 streaks and spiral color zones with hint of a peripheral spiral yellow 

 fillet as in the sultanus and interruptus phases of A. perversus. The 

 color pattern of A. comes is similar. Specimens from Prachuab 

 Kirikhan have purplish banding on the upper whorls that is similar 

 to that found in A. janus. No other color variations require special 

 comment. 



Size and shape variation is summarized in table 2. While there 

 are great differences in size and shape between, for example, the 

 Nong Khor and Prachuab Ku'ildian populations, this probably 

 reflects local ecological conditions rather than true geographic varia- 

 tion, since the Kao Sabab, Kao Bantad, Krat, and Kao Lem Sing 

 samples from Eastern and Southeastern Thailand are in the size 

 range of the Prachuab Kii-ikhan population rather than the dwarfed 

 shells from the Sriracha area. Specimens of Amphidromus schom- 

 burgki from Srii-acha are similarly dwarfed when compared with 

 Pak Chong examples (see above), and it is probable that the Sriracha 

 region is a marginal area for Amphidromus. 



Variation in A. atricallosus within Southeast Thailand, for example, 

 is much greater than dift'erences (except in color frequency) observed 

 in comparing specimens from the different zoogeographic areas of 

 Thailand, and there thus seems to be no basis for recognizing sub- 

 species. Possibly collections from the Tenasserim area may result 

 in delineating a moderately restricted geographic range for the 

 atricallosus predominance, but, in view of the great color variation, 

 I would hesitate to create subspecies on color pattern frequencies. 



Some strikingly colored shells from the Anambas Islands are 

 referred to the leucoxanthus pattern. One from Pulo Telaga (USNM 

 161934) and sLx adults from Pulo Riabu (USNM 161923) are most 

 similar to the orange shells figured by Pilsbry (1900, pi. 54, figs. 78-79). 

 Possibly these are the "A. chloris" reported by Jacobi (1895) from 



' This locality of de Schauensee should not be confused with the Kao Luang 

 west of Nakon Sritamarat that was visited by Smith. "Khao Luang" is the 

 same as Smith's Kao Luong. 



