140 PROCEEDINGS OF THE ACADEMY OF 



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 m}' 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 m} T 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 



