336 Lingual Dentition a7id Anatomy of 



longitudinal lines of reinforcement), again enlarged at apex, which is re- 

 flected, slightly produced, and bluntly tricuspid, the outer cusps almost 

 obsolete. The lateral teeth are subquadrate, more than twice as broad as 

 the centrals, the reflected portion greatly produced and bicuspid. There 

 are about eight perfect lateral teeth in Leptachatina grana, the formula 

 being 20-1-20. In Laminella hictnnsa the formula is about 22-1-22. In 

 L. Mastersi 26-1-26, with eight perfect laterals. The marginal teeth in 

 Laminella are mei'ely a simple modification of the laterals, they are low, 

 subquadrate, with one long, oblique, blunt inner denticle and two smaller, 

 outer denticles. In Laminella the denticles are more numerous and more 

 pointed. In all the Leptachatina the marginal teeth are of a difl'erent type. 

 They seem to have but one very broad cusp, whose outer edge is irregu- 

 larly digitate or fringed, the points being about eight, but varying in num- 

 ber and position. 



To illustrate the jaws and lingual membranes I have selected (fig. 10) 

 one central and one lateral of Laminella Mastersi, a group of centrals and 

 laterals of the same (flg. 11), with a group of marginals of the same (fig. 

 9.) Fig. 2 gives one central and several adjacent laterals, from either 

 side, of Achatinella prochtcta. Fig. 8 gives several marginal teeth of 

 Leptachatina nitida. Fig. 7, the jaw of Laminella Mastersi. Fig. 6, the 

 jaw of Laminella picta. 



It will be noticed that the lingual membrane of Newcomhia, Laminella 

 and Leptachatina resembles that of Stenogyra in its extremely small cen- 

 tral tooth. The jaw also is of the same type. 



The following species were found with embryonic shells in the oviduct, 

 usually only two in number and of very unequal size, Newcomhia picta, 

 Laminella decorticata, luctnosa, Part^ilina eburnea, tceniolata, Achatinella 

 producta. Hejaiemann, I.e., found them also in hulimoides. 



A peculiarity of the genus seems to be a perfectly black lung, in great 

 contrast to which are the two divisions of the heart and the renal organ, 

 all decidedly white. 



Another peculiarity of the genus is a short foot, broad in front, rapidly 

 narrowing towards the pointed tail. In Partrdina pallida, however, the 

 tail is long. Also in Partulina eburnea. In many of the specimens I 

 noticed an unusual development of the blind sac under the mouth (sup- 

 posed by Dr. Leidy to be the seat of the olfactory nerve). I believe this 

 to be a generic characteristic also. 



I noticed nothing unusual in the nervous ganglia, or in the digestive 

 apparatus, examining each system carefully in several species, the upper 

 portions of the digestive system especially in Partulina pallida. 



The reversion of the shell, common in the genus, seems accompanied by 

 a corresponding sinistral arrangement of the internal organs. Thus the 

 oriflce of generation, usually on the right of tlie animal in the snails, is, 

 in the sinistral Achatinellce, on the left. I have verified this fact in 

 eburnea, varia, lirida and Johnsnnii. 



So far as can be judged fi'om alcoholic specimens, it seems that the 

 external oriflce of the generative organs is usually under the mantle, not 



