§ 53. THE ACALEPHAE. 59 



ORDER 11. DISCOPHORA. 



They have a simple central stomach, and move by means of discoid or 

 campanulate contractions of their body. 



Family: Aeqdorina. 

 Genera : Acquorea, Polyzenia. " 



Family : Oceanidae. 

 Genera : Oceania, Cytaeis, Thaumantias. 



Family: Geryonidae. 

 Genus : Geryonia. 



Family : Riiizostomidae. 

 Genera : Cephea, Cassiopea, Rkizostomum. 



Family : Meddsidae. 



Genera : Pelagia, Cyanea, Chrysaora, Medusa, Aiirelia, Ephyra, SthenO' 



nia. 



ORDER III. CTENOPHORA. 



Their mouth and stomach is simple and central, and they move by means 

 of cilia arranged in longitudinal rows. 



Family: Beroidae. 

 Genera : Bero'e, Lesueuria, Medea. 



Family : Mnemiadae. 

 Genus : Euchavis. 



Family: Callianiridae. 

 - Genera: Cydippe, Cestum, 



BIBLIOGRAPHY. 



Eschscholtz. System der Acalephen. Berlin, 1829, 



Lesson. Histoire naturelle des Zoophytes. Acalephes. Paris, 1843. 



Will. Horae tergestinae oder Beschreibung und Anatomic der im 

 Herbste, 1843, bei Triest, beobachteten Acalephen. Leipzig, 1844. 



Ehrenberg. Ueber die Acalephen des rothen Meeres und den Organis- 

 mus der Medusen der Ostsee, in the Abhandlungen der Bed. Akad. 1835. 



Mertens. Beobachtungen und Untersuchungen iiber die beroeartigen 

 Acalephen, in the Memoires de I'Academie des Sciences de St. Peters- 

 burg, 6me series, Tom, II. 1833, p. 479. Also, in Isis, 1836, p. 311. 



Brandt. Ausfiirliche Beschreibung der von C. H, Mertens auf seintfr 

 Weltumsegelung beobachteten Schirmquallen, nebst allgemeinen Bemerkung- 



