GASTROPODA. ^ t 



PLEUROTOMA (CRYPTOCONUS) IRRAVADICUS, Spec. nov. t 



Plate IX, Fig. 6— 6a, 



Unfortunately none of the three specimens under examination 

 are completely preserved, but, although fragmentary, they are suffi- 

 cient to show the distinctive features ; the shell is mitriform, consist- 

 ing of flat, rather high whorls, with a sharp suture ; the ornamenta- 

 tion is rather remarkable ; it consists chiefly of revolving ribs, which 

 show a peculiar arrangement; two of moderate strength run quite 

 close to the suture ; below these follow five very fine lines quite close 

 together, which mark the position of the slit ; below these follow 

 three ribs of the same strength as those near the suture, between 

 which there are two more delicate ones; then follow at least 10 

 equidistant stronger ribs. On the spire, and much less distinctly, on 

 the body-whorl, they are crossed by fine longitudinal ribs, which thus 

 produce a kind of indistinct reticulation and obsolete nodules on the 

 crossing points. Aperture unknown. 



Locality. — Rare at Minbu. 



Remarks.— To judge from the ornamentation only, this species 

 seems to belong to the sub-genus Cryptoconus, a supposition with 

 which the position of the slit close to the suture would fully agree ; 

 more and better preserved specimens are, however, required to decide 

 this question. 



PLEUROTOMA (DRILLIA) INTERRUPTA, Lam, Plate X, Fig. 1—2. 



1883—87. Pleurotoma (Drillia) interrupta, K Martin, Beitrage zur Geologie Ost- 



Asiens und Australiens, ist ser., vol. Ill, 

 page 65, tab. X., figs. 66, 67, 68. 



Only a few ill-preserved specimens have come under examination, 

 but they exhibit the features well enough to allow of identification. 

 The shell is small and fusiform ; the sculpture consists of longitudi- 

 nal nodules, which are crossed by fine revolving ribs, one of which 

 runs quite close to the suture above the slit, finer lines are occa- 

 sionally seen in the rather broad interstices. 



Locality, — Rare at Yenangyat and Minbu. 



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