1<S95.] NATURAL SCIENCES OF PHILADELPHIA. 239 



All these are practically indistinguishable, except that those 

 marked with an asterisk seem to have a central tooth. 



(I)). Jaw arcuate, strong,, not ribbed. Radula oblong, not wide. 

 Teeth quadrate, in nearly straight rows. Centrals small, narrow, 

 sometimes faintly tricuspid; laterals larger, bicuspid; marginals 

 bicuspid or multicuspid as in Helix. 



To this section belong: 



Achatinella assimilis Xewc, 



27.1.27X98 5,390 

 A. h( Ivina Bald. ■;._>. i..;j x 108=7,020 

 A. labiata Newc. 

 . 1. Masti rsi Newc. 



A. nana Bald. 



A . pullata Bald . 28. i.js x 99=5,643 



A . si m ih iris Hartm. 



A. umbrosa Bald. 



Here again, though there are small differeuces in the number of 

 teeth, the varieties of shape are very trifling. The central tooth of 

 A. helvina is a little wider than usual, and the marginals of .4. 

 umbrosa take a peculiar form; but neither of these variations seems 

 important. 



On the Dentition of some new Species of Heeicter. By 



Henry Suter. 



Some time ago Mr. D. D. Baldwin kindly sent me the animals of 

 some species of Reliefer for examination of their dentition, and I 

 herewith give a short report. 



Helicter (Apext Cookei Baldwin. 

 Helicter iBulimella) Lyonsiana Baldwin. 

 Helicter (Partulina) Dolei Baldwin. 



These three species perfectly agree in the peculiarity of their 

 dentition. There is no jaw, only a chitiuous, transparent membrane 

 PI. XI, fig. 55, a, covering the lips. The radula, PI. XI, tig. 55, b, 

 forms a tube, compressed sidewise, with numerous folds; part of it 

 »> bent backward anteriorly, forming a collar. The teeth of the 

 radula PI. XI, fig. 52, oc 1 oo, form oblique rows at an angle of 

 about 80°. The rhachiclian tooth is long and slender, with a small 

 reflection and two minute cutting points in II. Lyonsiana, no reflec- 

 tion could be seen in the two other species. The laterals and mar- 

 ginals are all alike, the denticles varying in number from five to 

 six, in the last marginals from four to two; these teeth very much 

 resemble the marginals of Succinea. The dentition is the same in 



