EEPORT ON THE DEEP-SEA MEDUSAE. 1 



DESCRIPTION OF THE SPECIES. 



Class I. CRASPEDOT^E, Gegenbaur, 185G. 



CRYPTOCARPiE, Eschscholz, 1829. GYMNOPnTHALMiE, Forbes, 1848. 

 Hydromedus*, Carus, 18G3. Aphacell.e, Hreckel, 1878. 



Medusae without gastral filaments or phacellaa ; with ectodermal genitalia (or sexual 

 products formed from the external germinal layer) ; with a true velum (always without a 

 velarium) ; without true marginal lobes of the umbrella; with double centralised nerve-ring. 

 Phylogenetic descent (probably universal) and ontogenetic descent (now established for 

 the majority) derived from hydroid-polyps without gastral filaments or from hydrostomEe. 

 Ontogenesis chiefly alternation of generations, often with metamorphosis. The sexual 

 craspedote generation is formed by lateral gemmation from the asexual hydrostoma 

 generation. 



Order I. ANTHOMEDUSiE, Heeckel, 1877. 



Craspedotse without marginal vesicles and otolites, with ocelli at the bases of the 

 tentacles. Genitalia in the external or oral wall of the stomach. Number of the radial 

 canals almost always four, very rarely six or eight. Ontogenesis chiefly alternation of 

 generations, often with metamorphosis. The trophosome of the asexual generation is a 

 hydroid-polyp of the order Tubularise. 



Family, Maegelid^ Hseckel, 1877. 



MAEGELiDiE, Hasckel, System der Medusen, 1879, p. 68, taf. v., vi. 



Anthomedusas with four or more simple or branched oral styles, with four or eight 

 separate genital sacs in the wall of the stomach, with four narrow simple radial canals, and 

 with simple unbranched tentacles, which are sometimes distributed equally, sometimes 

 grouped in four or eight bundles. 



Sub-family, Thamnostomid^e, Hseckel, 1867. 



Margelidee with branched or compound oral styles, and tentacles equally distributed,. 

 not grouped in bundles. 



Thamnostylus, 1 Hseckel, 1879. 



Margelidse with branched or compound oral styles and only two opposite perradial 

 tentacles. 



1 &xfivo;, bush ; tnv?.o:, style. 

 (ZOOL. CIIALL. EXP. — PART XII. 1881.) M 1 



