xxiv. CONCHYUA—DJTHYRA 



** Cochlearibus horizontali-protensis. 



with the teeth projecting horizontally. 



4. declivis, latere antico truncato. 



the anterior end truncate. 



5. praetenuis, latere antico rofimdaio. 



the anterior end rounded. 



7. arctica, latere pastico truncato. 



the hinder end truncate. 



6. distorta, margine simiato. 



the margin indented. 



15. LiSTERA. 



1. compressa, Listera. 



16. Amphidesma. 



1. prismaticum, valvd altera denticulo simplici et laterulihus. 



in one valve a simple denticle and lateral teeth. 



2. teiiiie, rnlva altera denticulo Jisso et later alibiis . 



in one valve a cloven denticle and lateral teeth. 



3. Boysii, talvd altera denticulis duobus et lateralibus. 



in one valve two denticles and lateral teeth. 



17. Agina. 



1. i)iiij)iirea, Agina. 



10. Ervilia. 

 1. nitens, Ervilia. 



