146 proceedings of the academy op 



On Classification. 



The characters of the jaw, combined with those of the lingual 

 membrane, furnish reliable bases of classification. They have 

 been considered of various weight by different writers. I here 

 propose to treat them as guides only to the greater division of the 

 Pulmonata.^ In grouping the various genera it will be necessarj'^ 

 to include all^ both American and foreign to America, in order to 

 properly appreciate the value of this grouping. 



Taking, therefore, the whole series of known terrestrial Pulmo- 

 nata, the first grand division is based on the presence or absence 

 of a jaw. Of the former are the following: Testacella,- Daude- 

 bardia'' Streptaxis,^ Bhytida,^ Diplomphalus^^ Strebelia V Glan- 

 dina,^ Petenia?^ Spiraxis?^" Streptostyla,^^ BaveniaV^ Strepslos- 

 tele^^^ GseliaxisV^ Gonospira^^ GibhuaV^ Ennea.^'' 



All the above have aculeate marginal teeth; the lateral teeth 

 are always absent; the centrals in some of the genera. 



The following genera have quadrate marginal teeth: Onchi- 

 dium^^^ Onchidella^^ Peronia^~^ BuchananiaP^ 



' I must not be understood to propose a system of classification. I mei'ely 

 place the genera into certain groups, independent of their divisions into 

 families. 



2 TIeynemann, Malak. Blatt. X., pi. II., fig. 5. 



3 Goldfuss verh. Naturh. Vereius der preuss. Rheinl. und Westphalens, 

 13th year, 1856, pi. VI., fig. c. c\ 



* Heynemann, Malak. Blatt. XV., pi. IV., fig. 2. 



5 Semper, Nachr. der deut. Malak. Gesellschaft II., 102. 



8 Fischer and Crosse, Jouru. de Conch. XXI., 21, pi. III., fig. 8. 



' Jaw and dentition unknown. ^ See this paper. 



3 Jaw and dentition not actually known. 



'" Jaw and dentition not actually known ; as restricted, the genus may be 

 more correctly placed near Sienogyra. 



" Fischer and Crosse, Moll. Mex., p. 16, pi. IV., fig. 2. 



'2 Jaw and dentition not actually known. 



'* Hej^nemann, Nachr. mal, Gesel. I. 20, 177, fig. 5. 



'* Jaw and dentition not actually known. 



'5 Bland and Binne}', Amer. Journ. Conch. V. 37, pi. XI. fig. 1, photo- 

 graphed. '^ No doubt like the last. 



" Heynemann, Nach. mal. Gesel. I. 20, 177, pi. XX., figs. 3, 4. 



18 Bland and Binney, Ann. Lye. N. H. of N. Y. X., p. 340, pi. XVI., 

 figs. 3-0. 



'9 Heynemann, Malak. Blatt. X., pi. III., fig. 18. 



2° Quoy, Voy. de I'Astrolabe, pi. XII. ^i jaw and lingual unknown. 



