[Extracted from the Proceedings of the Academy of Natural Sciences of Philadelphia, 
April 27, 1875.] 
ON THE JAW AND LINGUAL MEMBRANE OF NORTH AMERICAN 
TERRESTRIAL PULMONATA. 
BY W. G. BINNEY. 
In his work on the “ Terrestrial Air-breathing Mollusks of the 
United States,” my father paid great attention to the jaws and 
lingual membranes, figuring those of all the species which he could 
obtain. In continuing my father’s labors on the same subject, I 
have described and figured those of many other species. Thus, in 
a certain sense, it may be said that a great deal is known of these 
organs in our land shells. Unfortunately, however, these figures 
and descriptions have become of comparatively little value now 
that the study of this subject has assumed such importance. They 
do not give in sufficient detail the character of the individual teeth, 
however correct an idea they may give of the general arrangement 
of the teeth upon the membrane. I have, therefore, been induced 
to review the whole subject, and present it in a manner which will 
be of value as throwing light upon classification. 
The following pages contain the result of my re-examination of 
the lingual membranes collected by me during the last thirty years. 
I regret that the collection is not more perfect, but there seems 
little chance of my making it more so, especially as to the rarer 
and more inaccessible species. I have decided, therefore, to pub- 
lish at this time what material I have. 
Before commencing my description, I will give some general 
remarks on the organs treated of in my paper, and on their value 
for the purpose of classification, and on the bibliography of the 
subject. 
GENERAL REMARKS. 
As many of my readers are quite unfamiliar with the subject, 
especially most of those who have so largely contributed specimens 
for examination, I will describe in detail the position of the organs 
and the method adopted for their study. 
On holding up against the light an individual of Helix thyroides 
in one hand, and offering to him with the other some food (a piece 
of carrot is always acceptable), one can readily see with the naked 
