141 



Genus 5. CRASSATELLA, Lamarck. 



Animal ; mantle-lobes united only by the branchial septum ; inha- 

 lent margins cirrhated ; foot moderate, compressed, triangular, 

 grooved ; gills smooth, unequal. (Woodward.) 



Shell; equivalve, everywhere closed ; hinge composed of two central 

 teeth in one valve and one in the" other, and a deep central 

 pit containing the ligament ; an obscure lateral tooth in each 

 valve. 



A beautiful genus, having shells of solid growth covered by a very cha- 

 racteristic chestnut-brown epidermis, often richly toned and rayed, and 

 sometimes developed in elegant concentric furrows. The ligament is 

 strong, contained in a conspicuous central pit, as in Mesodesma, but not 

 so perpendicularly produced. The animal differs in not having the lobes 

 of the mantle united. Most of the Crassatella are Australian, but the 

 genus is well represented in the Eastern Seas, as well as on the western 

 coast of South America and in the West Indies. 



1. Antillarum, Reeve. 



2. bellula, Adams. 



3. castanea, Reeve. 



4. compressa, Ad. fy Rv. 



5. compta, Adams. 



6. concinna, id. 



7. Corbuloides, Reeve. 



8. corrugata, Ad. 8f Rv. 



9. Cumingh, Adams. 



10. decipiens, Reeve. 



11. divaricata, Chemn. 



Species. 



12. Donacina, Lam. 



13. gibbosa, Sow. 



14. jubar, Reeve. 



15. Kingicola, Lam. 



16. lsevis, Adams. 



17. lapidea, Reeve. 



18. nana, Ad. 8f Reeve. 



19. obscura, Adams. 



20. ornata, Gray. 



21. pallida, Ad. 8f Reeve. 



22. picta, id. 



23. pulchra, Reeve. 



24. radiata, Sow. 



25. rostrata, Lam. 



26. speciosa, Adams. 



27. subradiata, Lam. 



28. sulcata, id. 



29. triquetra, Reeve. 



30. truncata, Adams. 



31. undulata, Sow. 



32. ziczac, Reeve. 



Figure. 



Crassatella pulchra. PI. 39. Fig. 215. Shell, with one valve dropped 

 to show the central tooth and ligamentary pit. 



