GASTROPODA. 23 



of growth are here sometimes, but not always, a little more distinctly 

 and regularly marked so as to form very fine plaits. 



NATICA CALLOSA, Sow., Plate V, Fig. 8— 8a. 



1840. Natica callosa, Sowerby, Transact., Geol. Soc. of London, and Ser., vol. V, 

 plate XXVI, fig. 3. 



The sub-globular shell consists of five whorls which form a very 

 low spire and a large ventricose body whorl ; the suture is not 

 very well marked ; the surface perfectly smooth, except some occa- 

 sional striae of growth ; aperture obliquely elliptical ; outer lip sharp ; 

 inner lip thick, callous, partly covering a deep umbilicus. 



Locality. — Common at Minbu, rare at Yenangyat. 



Remarks. — This species apparently attains a larger size than 

 Natica obscura, and is easily distinguished from that form by the 

 exceedingly low spire which hardly projects over the last whorl. 



SIGARETUS (P) BICOSTATUS, Spec, nov., Plate V, Fig. g-ga. 



Only one specimen has come under examination and this is by 

 no means well preserved ; the small shell of obliquely globular 

 shape consists of about four whorls ; the spire is very low, the last 

 whorl large and ventricose ; the sculpture is formed by fine revolving 

 ribs which are separated by interstices of the same breadth, some- 

 times, particularly in the upper part of the last whorl, a fine filiform 

 rib is intercalated between two stronger ones; aperture large, 

 elliptical ; outer lip sharp ; inner lip probably sharp. 



Locality. — Very rare at Yenangyat. 



Remarks.-*-The generic position of this species is not quite 

 certain, because the features of the aperture are only indistinctly 

 known ; the sculpture of the surface however distinguishes this 

 species readily enough. 



CERITHIUM, 8p., Plate V, Fig. to— 10a. 



A fragment of a turreted shell probably represents this genus; 

 the whorls are loW| slightly inflated and covered with four or five 



1 23 ) 



