with a revision of the Limnceidce of Authors. 341 



Buccal plate arcuate, smooth, dark reddish brown. Lateral plates 

 bluntly pointed. 



Animal resembling Z,imncea, with a more slender foot, posteriorly 

 rounded. 



Cusp of central tooth trilobed, the central lobe most prominent. 

 Base strongly bilobed behind. First three laterals have the cusps 

 strongly bidentate, the inner lobe having a notch on the inner side. 

 This side is more strongly notched twice, in the next three laterals. 

 In all, the cusps are longer than the base. Seventh and eighth late- 

 rals have four denticles on the cusp, two larger than the others. The 

 ninth and tenth have five denticles, and the cusp of the eleventh is 

 prolonged with six denticles. The two remaining pleurals are similar. 

 The two inner uncini have an oval base, produced anteriorly, and five 

 or six denticles on the rhachidian side. The next is bidentate at the 

 tip and shorter, and the outermost is quite short and simple. The 

 formula is 4.13.1.13.4. There are about sixty rows. 



The ribbon is narrower than in Limncea, and the shape of the 

 rhachidian tooth differs slightly. These, with the characters of the 

 shell, are hardly sufficient to constitute it as a distinct genus. 



Amphipeplea (glutinosa). 



Buccal plate arcuate, smooth. Two lateral accessory plates. 



Tentacles triangular, moderately elongate ; eyes sessile on their in- 

 ner bases. Genitalia on the right side. 



Mantle much produced, nearly enveloping the shell. Foot bluntly 

 l'ounded behind. 



Ova deposited in kidney-shaped or cylindrical masses of jelly. 



Teeth. Laterals; first eight, quadrilobate, broad, with cusps very 

 lon<* in proportion to the base. The remainder with rhomboids.] cusps, 

 with from two to five denticles on the end, and one somewhat poste- 

 rior to the rest, on the outer side of the cusp. Central tooth apparent- 

 ly simple. Formula, 24.1.24. 



Shell few whorled, dextral, with a short spire, and the lasf whorl 

 much inflated. 



Planorbis (corneus, lentus). 



Buccal plate arcuate, crenulate. Two narrow, <h:licate accessory 

 plates. 



