120 PEOVISIONAL AID TO THE STUDY OF TASMANIAN MOLLUSC A. 



VI. 



10. Linear, narrow 



11. Quadrate, squarish 



12. Patulous, dilated at its entrance 



13. Compressed, diminished at its en- 

 trance 



14. Produced, lengthened out 



15. Sometimes truncated, stunted, cut 

 short abruptly at the end 



Peristome. Sometimes peritreme 

 Margin of aperture. It is : — 



1. Continuous or entire, as in 



2. Interrupted, when the left side of 



aperture is formed only by the 

 body- whorl ... 



3. The left side is formed either by the 

 inner or columella lip (labrum) 

 or partly by the body-whorl or 

 parietal wall. The right side is 

 formed by the outer lip (labrum.) 



VII. Outer lip may be : — 



1. Thin and sharp 



2. Thickened 



3. Eeflected, curled outwards 



4. Inflected, curled inwards 



5. Expanded, swollen 



6. Digitate. 



7. Foliated, fringed with spines. 



8. Emarginate, incised, or slit 



9. Effuse, when basal or anterior 



extremity is slightly produced, 

 depressed, or reflected 



10. Sinuous, bent or curved interiorly. 



It may be : — 



11. Dentate, toothed 



12. Plicate or lamellate, when the teeth 

 become rib-like. 



13. Eingent, having large plications, 

 nodules or teeth. 



14. Deflected, deflexed, bent aside or 

 backwards. 



VIII. Inner lip or columella margin may 

 have characters like those described 

 under outer lip. 



IX. Umbilicate. Perforate. When the 



base of the axis or columella, around 

 which the whorls are coiled, is open 



Example fig.. 

 No. 



26 

 13 



2 d 3= 

 5, 6, 33-34 



8, 9, 21, 44 



5 



7 

 1 



8 



25 



1 



3» 



32, 33, 34 



3,29 



