Mr. A. Adams on Cavolina, Diacria, and Pleuropus. 45 



6. C, longirostris, Lesueur. 



Hyalaea limbata, B*Orb. 

 ecaudata, Lesueur. 



Hab. Atlantic and Indian Oceans ; China Sea. The H. ecau- 

 data of Lesueur is only a short-beaked variety, and D'Orbigny's 

 H. limbata is merely a large variety. 



7. C angulatay Souleyet. 



Hab. Indian Ocean. Common. This offers some peculiari- 

 ties, but seems merely to be a small variety of C. longirostris, 



8. C Orbignyiy Rang (fossil). 

 Hyalsea aquensis, Gratel. 



Subgen. Or^bignyia, A. Ad. 



9. C. inflexa, Lesueur. 



Hyalsea elongata, Lesueur. 



? depressa, D'Orb. 



uncinata, Honing h. 



vaginella, Cantr. 



Hab. Atlantic and Indian Oceans. Rather abundant. 



10. a labiata, WOrh. 



Hab. Atlantic and Indian Oceans and China Sea. Less 

 common than the former. 



These two species are Cavolinee much elongated, and present 

 a peculiar appearance compared with the typical forms. 



Gen. Diacria, Gray. 

 1. D. trispinosaj Lesueur. 



Hyalsea mucronata, Quoy & Gaim. 



triacantha, Guidotti. 



depressa, Bivona, 



Hab. Common in the Atlantic and Indian Oceans. 



Gen. Pleuropus, Eschsch. 



1. P. pellucidus, Eschsch. 

 Cleodora pleuropus, Rang. 

 Hab. ? Mediterranean. 



2. P. longifilisj Trosch. 

 Hab» Mediterranean. 



