^ 53. THE ACALEPHAE. 59 



ORDER II. DISCOPHORA 



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

 campanulate contractions of their body. 



Family: Aequorixa. 

 Genera : Aeqzcorea, Polyxenia. 



Family : Oceanidae. 

 Genera : Oceania, Cylaeis, Thanmantias. 



Family: Geryonidae, 

 Genus : Geryonia. 



Family : Eiiizostomidae. 

 Genera : Cephea, Cassiopea, Rhizostomum. 



Family : Medusidae. 



Genera : Pelagia, Cyanea, Chrysaora, Medusa, Aurelia, 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: Beroi', Lesueuria, Medea. 



Family: MStemiadae. 

 Genus: Eucharis. 



Family : Callianiridae, 

 Genera : Cydippe, Cestuvi. 



BIBLIOGRAPHY. 



Eschscholtz. System der Acalephen. Berlin, 1829. 



Lesson. Histoire naturelle ^des Zooj^hytes. Acalephes. Paris, 1843. 



Will. Horae tergestinae oder Beschreibung und Anatomie 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 derBerl. Akad. 1835. 



Mertens. Beobachtungen und Untersuchungen über die beroeartigen 

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

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



Brandt. Ausfürliche Beschreibung der von 0. H. Mertens auf seiner 

 Weltumsegelung beobachteten Schirmquallen, nebst allgemeinen Bemerkung- 



