124 THE VOYAGE OF H.M.S. CHALLENGER. 



Second Sub-order of Discomedus^e, SEMOSTOMiE, L. Agassiz, 1862. 



Flag-mouthed Discomcdusse. Discomcdusse with four large, perradial, folded oral arms, 

 with simple, central oral opening, and with long hollow tentacles. 



Family, Cyaneid.e, L. Agassiz, 1862. 

 Cyaneid.e, Hfeekel, System der Medusen, 1879, p. 518, taf. xxx. 



Semostomse with broad radial pouches, and branched, csecal lobe canals, without 

 coronal canal. Discomeduste with simple, cruciform, central oral opening, surrounded by 

 four perradial, folded oral arms. Stomach with sixteen or thirty-two broad radial pouches, 

 whose distal margin is cleft into thirty-two or sixty-four branched lobe pouches ; the 

 branches of the latter are csecal, not anastomosed ; no coronal canal. Genitalia, four 

 waved bands or frills in the oral gastral wall, usually in the form of wide sacs, hanging 

 freely and without sub-genital cavities. Sixteen to thirty -two or more marginal lobes ; 

 eight or sixteen sense clubs (four perradial and four interradial, with sometimes also 

 eight adradial). Tentacles long and hollow, eight or more in number. 



Sub-family, Drymonemid^e, Hseckel, 1879. 



Cyaneidse with eight sense clubs (four perradial and four interradial), which lie 

 distant from the umbrella margin in deep niches of the subumbrella ; also with numerous 

 tentacles, which are scattered almost over the whole subumbrella, but are wanting in 

 the marginal lobe zone. 



Drymonema, Hseckel, 1879. 1 



Cyaneida with 8 sense clubs, lying far from the umbrella margin, in deep niches 

 of the subumbrella. Tentacles very numerous, irregular, scattered almost over the 

 whole surface of the subumbrella and inserted in deep radial furrows, between numerous 

 strongly dendritically branched subumbral radial ribs. Sixteen broad, radial canals ; these 

 are very short, their thirty-two lobe pouches, and the dichotomous canal branches of 

 the latter, proportionately more strongly developed. 



The genus Drymonema is as yet only known from the Mediterranean deep-sea species 

 described below, and is so strikingly distinguished by many peculiarities from the other 

 Cyaneida?, that it represents a special sub-family of them, the Drymonemidas. Whilst 

 in all other Cyaneidse the peripheric tentacle zone remains separated from the peripheric 

 margin of the central stomach by a broad coronal muscle, which is usually laid in many 



1 Atpvpo; = a wood ; i/iifat = threads. 



