GUDE : OH THE ARMATURE OF LAND MOLLUSCA. 57 



the columella, which bears two, well-developed lamellee, the inner 

 one with two or three sharp points ; the second high, shaped like 

 a sharp tooth ; in addition, there are seven rather stout elevated 

 lamellae on the palatal wall, evenly distributed. E. pseudoleioda, 

 Sut., is furnished with three folds on the parietal wall, one columellar 

 and eight palatal plicae, while E. wairarapa, Sut., with five parietal 

 and one columellar lamellae, has no less than ten palatal plicae. 



The subgenus Helenoconcha, Pilsbry, also a small group, is only 

 found in St. Helena. E. jwlyodon, Sowerby, has three, revolving, 

 entering lirae on the parietal wall, the upper and lower frequently 

 double ; there are about seven palatal plicae, which are rather evenly 

 distributed and extend some distance within. E. miniitissima. 

 Smith, has as many as six parietal lirae and from eight to ten palatal 

 plicae. The last Endodont subgenus to be considered is Afrodonta, 

 M. & P., with some six known species found in South Africa. 

 E.trilamellaris, M.& P., possesses three, short, low folds, one parietal, 

 one palatal, and one basal. 



The Pyramiduloid subgenus Helicodiscus, Morse, is restricted to 

 North America, and contains four or five known species. P. 2mrallela, 

 Say, has radial series of two or three horizontal palatal teeth, these 

 series being about one-third of a whorl distant from each other. It 

 is probable that the earlier series are absorbed by the animal as the 

 growth of the shell proceeds. In P. fimbriata, Weth., the series con- 

 sist of a vertical, stout lamella on the outer wall and a smaller 

 oblique one on the basal wall. 



Genus Ruthvenia, Gude, 



was originally established as a section of Plectopylis until Lieut. -Col. 

 Godwin-Austen investigated the anatomy and concluded that it 

 was allied to Thysanota. Five species are known, four of these 

 occurring in Ceylon and one in Southern India. They are small, 

 fragile shells, bearing two series of small, horizontal, callous denticles 

 on the palatal wall and a solid, transverse plate on the parietal wall. 

 In some forms additional transverse denticles are found on the 

 palatal wall. 



The important and large group of Helicid^ next demands con- 

 sideration, the first genus to be reviewed being 



Genus Ashmunella, Cock. & Pils. 



This genus, of about thirty species, is restricted to the United 

 States. A. tJiomsoniana, Anc, is provided with one oblique, parietal 

 denticle, one transverse plate on the outer margin of the peristome, 

 and two denticles on the lower margin. A. levettei, Bid., has a short 

 oblique, parietal fold, one transverse fold on the outer margin of 

 the peristome, and two short, horizontal plicae on the lower margin. 



