136 ACALEPIIS IN GENERAL. Part I. 



of the observer to trace tlieir lii.storv. But -when the naturalist who devotes 

 years to their study is not only an eminent physician, Init at the same time a 

 minute, accurate, and philosophical observer, pursuing his task under the most 

 favorable circumstances, great results may be expected. This Avas the case of 

 Eschscholtz, who, during two voyages ai'ound the world, applied himself chietly to 

 the investigation of these animals, and had Ix'tter opportunities for studying their 

 various types in their natural element than any other man had enjoyed before, 

 not even excepting Peron and LeSueur. Aside from the large amount of infor- 

 mation it contains, the " System der Acalephen " of Eschscholtz is a model work 

 for the manner in which the sulyect is treated. Full, minute, ex])licit, decided, 

 where he speaks from personal oljservation ; unpretending, candid, and fair, Avhere 

 he alludes to the investigations of other distinguished authors ; cautious and I'eserved 

 where he has reasons to question the coi-rectness of the statements of others, — he 

 secured the admiration of his contemporaries and the gratitude of his ibllowers, 

 and those who have known him lament his early loss. 



CLASSIFICATION OF ESCHSCHOLTZ, 1829. 



The limits of the class of Acalc|)lis, as cii-oumsoribed by Escliseholtz in 1820, coinci<lo with tho>e 

 assigned tu it by Cuvier from the lieginning, -with the only exeeplion that the Actinia' an/ excluded. 

 The Ilydroids are entirely ignored by Eschscholtz, as if tliey had no relations to the Acale[)hs. He 

 divides, for the first time, this class into three natural orders, and distinguishes a number of natural 

 families. All later classifications of the Acalephs are mere modifications or improvements of that of 

 Eschscholtz. 



1st Order. CTKNOrnoRyF,. 



1st Family. Ca!lianirid;Tj, with three genera: Cesfum, Cydippe, Callianira. 

 2d Family. Mnemiida; : Eucharis, Mncmia, Calynuna, Axiotima, 

 ,jd F^amily. Beroid<B: Beroe, Medea, Pandora. 

 2d Order. DiscoPUORiE. 



First Division. Discophorw phanerdcarpte. 



1st Family. Rh i zostomida' : Cassiopca, Rhizostoma, Cephea. 



2d Family. ISIedusidiv : Sthenonia, JMedusa, Cyanea, Pelagia, Chrysaora, Ephyra. 

 Second I)i\ision. Discop/iorrr cnjptocarpcc. 



1st Family. Geryonida> : Gcrj'onia, Uiana'a, Linuche, Sapheuia, Eirene, Lymnorea, Favonia. 

 2d Family. Oceanidaj : Oceania, Callirhoe, Taumantias, Tima, Cyta;is, Melicertum, Phor- 



cynia. 

 .'h1 Family. j-lMiuorida' : jF'<iuorea, Mesonema, ^Egina, Cunina, Ivirybia, Polyxena. 

 ■1th Famil}-. IJeren icid;e : Eudora, llcrenice. 

 3d Order. Sii'iiONofiioit.K. 



1st F'amily. Diphyid;e : Eudoxia, Ersa^a, Aglaisnui, Abyla, Diphyes, Cymba. 



2d Family. Pliysojihorida' : A|ioh'mia, I'hysophora, Hippopodius, Rhizoiih^sa, Epibnlia, 



Agalma, Athorybia, Stcphanomia, Uiscolabe, Physalia. 

 3d Family. Velellida- : Rataria, ^'eh•^a, I'orpita. 



