REPORT ON THE DEEP-SEA MEDUSAE. 133 



umbrella, usually with a distinct coronal canal. Four interradial genitalia in the aboral 

 wall of a central subgenital porticus, which has arisen from centripetal fusion of four 

 separate gastral, subgenital cavities. 



Sub-family, Leptobrachios:, L. Agassiz, 1862. 



Crambessidae without free upper arms, but with band-shaped, thin, greatly lengthened 

 lower arms, which are naked for the most part, and only bear a tassel-shaped bunch of 

 tuft-like funnel frills at the distal end. 



Leonura, 1 Hseckel, 1879. 



Crambessid without free upper arms, with band-shaped, very long, thin lower arms, 

 which are naked for the most part, and only bear a bunch of funnel frills towards the 

 distal end, above a naked terminal knob. The suture of the oral cross is eight-rayed, with 

 eight adradial funnel frills, forming a special rosette of tufts round the centre of the arm 

 disk. 



The genus Leonura (or Leontura), along with the closely-allied genus Leptohrachia, 

 compose the peculiar small group of the Leptobrachidse. L. Agassiz erected them (1862) 

 into a special famdy of the Rhizostonue, whilst it seemed to me more to the purpose to 

 attach them as a sub-famdy to the closely-allied family of the Crambessidaj (System, 

 1879, p. 630). This small group was hitherto known only by a single species, the 

 Rhizostoma leptopus (from the Radack islands), of which Chamisso and Eysenhardt gave a 

 tolerably good description in 1821 (Nova Acta Acad. Leop. Carol., torn. x. p. 356, pi. 

 xxvii). In 1879, I myself described the Crambessida Leonura leptura from New Zealand 

 as a closely-allied Rhizostom (System, 1879, p. 631). Leonura terminalis described 

 below (the only Rhizostom of the Challenger expedition) differs somewhat from Leonura 

 leptura. Whilst the structure of the umbrella only varies a little from Crambessa, 

 the eight long thin arms are distinguished by the retrograde formation of the fused 

 upper arms, and by the restriction of the funnel frills to the oral disk on the one side, 

 and the distal half of the arms on the other ; the proximal half of the arms lying between 

 them, is naked and without frills. 



Leonura terminalis, Hseckel (PI. XXXII. ). 



Leonura terminalis, Hfeckel, 1879, System der Mechisen, p. 646, No. 616. 



Umbrella depressed, with eighty marginal lobes (eight pointed triangular velar lobes 

 between two small diverging ocular lobes in each octant). Subgenital ostia two to three 

 times as broad as the intermediate pillars. Suture of the oral cross of the arm disk witli 



1 AeW=lion ; oupa = a tail. 



