150 



10. oblonga, Soto. 



11. obtusa, Leach. 



12. punctata, Conr. 



13. radiata, Sow. 



14. rostrata, Lam. 



15. striata, Q«oy. 



16. tabacea, Gronov. 



17. trilineata, /Say. 



18. unguiculus, Sow. 



Figure. 



Pandora rostrata. PI. 41. Pig. 223. Shell, showing the elongated 

 flexuously beaked growth of the posterior side. 



Genus 5. LYONSIA, Turton. 



Animal ; oblong ; mantle closed except a fimbriated opening ante- 

 riorly for the passage of a tongue-shaped grooved foot ; siphons 

 very short, united nearly to their orifices, which are fringed. 

 fForbes.J 



Shell; inequivalve, more or less inequilateral, truncated and a 

 little gaping posteriorly ; both valves convex, left valve rather 

 the larger ; surface of the shell often striated and invested ivith 

 an epidermis ; hinge composed of an oblique toothless 'plate in 

 each valve sustaining the ligament in connection with a detached 

 ossicle. 



The Lyonsice, like the Pandora, are few in number, widely and deeply 

 distributed. Though found in arctic, temperate, and tropical seas, only a 

 dozen species have been described, and they are not very well known 

 amongst collectors. The Mya Norvegica of Chemnitz [Lyonsia Norvegica, 

 Turton ; Osteodermia Corbuloides, Deshayes), inhabiting our North British 

 shores, is the type of the genus, and it may be readily distinguished from 

 Pandora by its more convex and less flexuously beaked form. The sur- 

 face is, moreover, striated, and covered with a very perceptible epidermis. 



1. anatina, Gray. 



2. arenosa, Moll. 



3. bracteata, Couth. 



4. Brasiliensis, id. 



Species. 



5. brevifrons, Sow. 



6. Chilensis, Phil. 



7. elongata, Gray. 



8. hyalina, Couth. 



9. nitida, Gould. 



10. Norvegica, Chemn. 



11. Solemyalis, Lam. 



12. striata, Bosc. 





