168 On the Systematic Arrangejnent of 



Subfamily Okthalicinj<: (p. 212). — The following de- 

 scription of the subfamily must be substituted for the one 

 given. 



Jaw composite, in numerous free, imbricated pieces, 

 usually with oblique sutures towards the centre of the jaw, 

 leaving an upper, angular, median piece. No median pro- 

 jection to the cutting edge, which is serrated by the lower 

 angles of the separate pieces. Lingual membrane Avith mar- 

 ginal teeth crowded, quadrate, usually broadly dentate. 



It will be observed that we include only in this subfamily 

 the genera whose jaw is actually in separate pieces, not those 

 in which the jaw is in one single piece, though in plates 

 formed by the ribs being arranged so as to give the appear- 

 ance of separate pieces. We do not, moreover, use the term 

 Orthalicinm in the same sense as Goniognatha of some 

 authors to comprise all the genera whose jaw has an upper 

 angular, median plate. This last form of jaw is found in 

 Cylindrella, Macroceramus, Pineria., and in some species of 

 Bidimulus, but not in Punctum. We do not recognize it 

 as of value in dividing the IMicidm into subfamilies. We 

 base this subfamily [Orthalicinm) solely on the free, imbri- 

 cated pieces of its composite jaw. 



The description of the genus Achatina (p. 212) is to be 

 entirely omitted. We adopt Liguus as a genus, and add the 

 following description of the jaw and lingual membrane. 



Jaw arcuate, ends attenuated, pointed ; composite, being 

 in numerous separate, free, imbricated, triangular pieces, 

 with sutures inclined obliquely to the centre of the jaw, so 

 as to leave an upper median, angular piece. Cutting edge 

 with no median projection, serrated by the lower angles of 

 the oblique pieces. 



Lingual membrane with long, quadrate teeth, pointed or 

 simply with a broad, recurved cusp. 



Orthalicus. — The following description of the lingual 

 membrane must be substituted for that given at p. 215. 



Long, broad, with numerous rows of long, four-sided, 



