PLATE VIII. 



Ctenodonta nasuta (page 35). 



Figure 1. Ctenodonta nasuta, Hall. Natural size. 



" 2. , — . Large specimen, with external ligament 



and hinge-teeth. 



Ctenodonta Logani (page 36). 



" 3. Ctenodonta Logani. Interior of left valve. 3a, the hinge enlarged. 



Ctenodonta contracta (page 37). 



" 4. Ctenodonta contracta. Var. with posterior sinus well marked. 

 4a, enlarged, to shew ligament. 



" 5. The same, with the sinus obsolete. 5a, the hinge enlarged, 



the muscular impressions deep. 



Ctenodonta gibberula (page 38). 



" 6. Ctenodonta gibberula. Interior and exterior of the left valve. 



Ctenodonta astart^formis (page 39). 



" 7. Ctenodontal astarteeformis. Left valve, outside and interior. 7a, 

 the hinge-line magnified. 



