28 ENDODONTA. 



Shell urabilicated, discoidal, with low-convex spire, rounded 

 periphery and rib-striated surface. Aperture crescentic, subverti- 

 cal ; outer lip thin, simple, armed a short distance within with 

 numerous low folds ; columellar lip bearing one or two larger enter- 

 ing lamellae, and parietal wall bearing one or two stout entering 

 plates, sometimes emarginate, or several smaller folds. Type E. 

 leioda Button. (PI. 4, figs. 30, 31, 32, E. aorangi Sut.). 



Jaw membranaceous, slightly arcuate, with distant vertical stride 

 (pi. 8, fig. 6, E. microundulata). 



Radula consisting of 90-100 slightly sinuous transverse rows of 

 teeth, the formula varying from 6-4-1-4-6 (wairarapa) to 10-7-1- 

 7-10 {aorangi}. Central tooth tricuspid. Lateral teeth similar, 

 tricuspid. Marginal teeth tricuspid or quadricuspid, the cusps 

 showing a tendency to coalesce on the outer ones (PI. 8, fig. 5, E. 

 microundulata). 



This group is closely allied to the Polynesian section Thaumato- 

 don. The species live under bark and rotten wood, in the bush. 

 Our knowledge of them is due to Professor F. W. Button and Mr. 

 H. Suter. 



E. leioda Hutt. viii, 87. E. hectori Sut. viii, 89. 



E. pseudoleioda Sut. viii, 88. magdalence Anc. 



E. wairarapa Sut. viii, 88. E. aorangi Sut. viii, 90. 



E. microuudulata Sut. viii, 89. E. hunuaensis Sut. 



Section Helenoconcha Pilsbry, 1892. 



Manual of Conch. (2), viii, p. 91. 



Shell discoidal, umbilicated ; aperture armed within with small 

 folds. Type H. polyodon Sowb., pi. 4, figs. 42, 43. Distribution, 

 St. Helena. 



Soft parts unknown. This group is distinguished from Thauma- 

 todon mainly on account of its different distribution. Its generic 

 relationships cannot be affirmed with certainty until the soft parts 

 are examined. It is not improbable that the species of Patula 

 described from St. Helena are toothless forms of this group. 

 E. polyodon Sowb. viii, 93. E. pseustes Sm. viii, 92. 



alexandri Fbs. E. biplicata Sowb. viii, 92. 



helenensis Pfr. E. vernoni Sm. viii, 91. 



E. minutissima Sm. viii, 94. E. bilamellata Sowb. viii, 91. 



E. leptalea Sm. viii, 95. v. unilamellata Sm. viii, 91. 



E. cutteri Pfr. viii, 93. 



