PLECTOPTLIS. 



89 



vertical plate on the parietal wall (see fig. 36 a), which appears 

 to be the remnant of the immature barriers formed before the 

 completion of the shell. A young specimen in my collection, 

 composed of five whorls, possesses the armature a little beyond 

 the place where four and a balf whorls have been completed ; the 

 barriers are almost identical with the mature ones, except that 

 the folds are smaller and the second and third palatal folds are 

 deeply bilobed. A still younger specimen of only four whorls has 

 the armature near the place when three and a half whorls have 

 been completed. 



II. Section Chers^cia, Gude. 



Chersaecia, Gude, Science Gossip, N. s. vi, 1899, p. 148. 



Sinistral or dextral. Umbilicus wide. Palatal folds horizontal 

 or oblique. Sometimes with one oblique or vertical plate. 

 Type, Helix leiopJiis, Benson. 

 Range. Assam, through Upper Burma and Laos to Tenasserim. 



86. Plectopylis muspratti, Gude. 



Pledopylis muspratti, Gude, Science Gossip, n. s. iv, 1897, p. 10, 

 fijr. 45 (shell and armature) ; ibid., Journ. Make, vii, 1898, p. 7, 

 fi-. .-3. 



Plectopylis {Chersaecia^ muspratti, Gnde, Science Gossip, n. s. vi, 

 1899, ij. 148. 



Original description : — " Shell sinistral, discoid, widely and 

 deeply umbilicated, pale corneous, streaked transversely with dull 



Fig. 37. — Plectopylis muspraifi. 



brown ; finely striated and decussated with spiral lines which are 

 very] distinct on the upper surface, but less so below. Suture 



