24 AMERICAN JOURNAL 



As for the manner of living it is the same for the Cylindrella 

 as for the Pupa and Clausilia, there is no uniformity. If the 

 large species of Mexico take pleasure in burying themselves under 

 dead leaves and lead a life almost subterranean, there are a 

 great many others who live on rocks or on plants. Then it is 

 not correct to generalize and to compare their mode of existence 

 with that of the Testacella and the Daudebardia. Moreover the 

 profusion with which certain species of Ct/lmdrella are strewn in 

 some localities, seems to exclude the probability of carnivorous 

 habits. For, and this is a remark which seems to apply to in- 

 ferior beings as well as to those of a superior organization, the 

 animals of prey generally live alone or disseminated in small 

 groups, while herbivorous animals have a marked tendency to 

 live in com'pany and to form large flocks. 



There is yet another serious objection that we find in the 

 system of classification of the pulmonate Mollusks based on the 

 similarities, and of differences of the lingual and buccal den- 

 tition, apart from conchological characters. 



Although this system might be completely founded — which is 

 not yet proved, we think, — it would still be wrong, in a prac- 

 tical point of vieAV, in the actual state of our knowledge, and for 

 this reason. This method of classification unites forms com- 

 pletely dissimilar, conchologically speaking, and separates 

 genera generally considered as neighbors, verjf loudly proclaim- 

 ing the little systematic value of the shell. Now, of the nine 

 or ten thousand living or fossil Pulmonifera actually described, 

 of how many species is the anatomy and the lingual and buc- 

 cal dentition, more or less perfectly known ? Not of two hun- 

 dred assuredly. 



But, let us even admit this number, which represents about 

 1-50 of the known Pulmonifera. By what right according to 

 that system, could the other 49-50, viz., almost the whole, be 

 allowed to be classed, having nothing else to be guided as to 

 them but the mere analogy of the conchological characters, 

 characters that the followers of the said system seem to sus- 

 pect, and reject almost entirely ? What would, for example, 

 happen, whenever the systematic position of a new and small 

 turriculated Pulmonate, whose animal is not known, had to be 

 determined, and by what reason should it be placed among 

 the Pup?e, rather than among the Cylindrellae, or the Clausilise, 

 since it would be admitted that the characters drawn from the 

 shell are without value ? It would lead, in the alternative, either 

 to an inconsistency in admitting characters theoretically not ad- 

 mitted, or to consider as not existing, scientifically the almost to- 

 tallity of known species. 



