Chap. II. CLASSIFICATIONS OF ACALEPHS. 139 



The history of the Acalephs has received very important accessions from the 

 investigations of Mertens, who was naturaUst in the Russian exploring expedition 

 of the Seniavin. Unfortunately he died before having published his labors ; and 

 the only paper he left so far finished as to have appeared nnder his name is 

 his " Beobachtungen und Untersuchungen iilscr die Beroeartigen Akalephen," in 2d 

 vol. 6* ser., Mem. Acad. Scien. Petersbourg. Brandt, who had superintended the 

 publication of this paper, afterwards worked up the materials left by Mertens 

 relating to the other families of the Acalephs, and gave a full account of them 

 in the " Ausfiihrliche Beschreibung der von C. H. Mertens, auf seiner Weltumse- 

 gelung beobachteten Schirmquallen," 4'= vol. Mem. Acad. Sc. Petersbourg. The value 

 of Mertens's eontrilnitions to the natural history of these animals may be inferred 

 from the simple flict, that Brandt, without having seen the Acalephs he describes, 

 could make elaljorate descriptions of them merely from the drawings and scanty 

 notes found among Mertens's papers. The tact is, the drawings of Mertens, and 

 those of his travelling companion. Professor Postels, are among the most accurate 

 and beautiful representations of Acalephs thus far published, and constitute by 

 themselves an ample atlas of the whole order of Discophora?. 



CLASSIFICATION OF BRANDT, 1833. 



Brandt, in his " Prodromus Descriptionis animalium ab H. Mertensio observatorum," published in the 

 Memoirs of the Imperial Academy of Sciences of St. Petersburg, in 1833, has the following classification 

 of the Acalephs, exclusive of the Beroids : — 



DISCOPHORiE. Medusid.e. 

 3Ionostom(B. 



Oceanidae : Circe, Conis. 



^quoridfe : jEquorea, Stomobrachiota, Mesonema, Zygodactyla, iEginopsis, Polyxenia. 



MedusidsB : Phacellophora ; Cyanea and Cyaueopsis ; Aurclia : Monocraspedon, Diplocraspedon ; 

 Pelagia, Chrysaora. 

 PolysfonuB. 



Geryonidaj : Geryonia, Proboscidactyla, Hippocrene. 



Rhizostomidaj : Cassiopea. 

 Incertce sedis. 



Berenicida; : Staurophora. 



SIPHONOPHOR.E. 



Dipliyida; : Diphyes. 



Physophorida^ : Physophora. 



Rhizophysida; : Epibulia : Macrosoma, Bracliysoma. 



Agalmidte : Agahna. 



Anthophysida; : Athorybia, Anthophysa, Apolemiopsis. 



Physalidffi : Pliysalia : Salacia, Alophota. 



Velellidaj : Vekllinte : Velella, Aristerodexia ; Poqntince : Porpita. 



