200 THE MEDUSAE. 



The lips, though simple, are considerably longer than Mayer has repre- 

 sented them, and extend almost across the bell cavity. 



Color. — The ocelli are reddish brown, the manubrium and gonads faintly 

 greenish. This is the same color that Mayer has recorded. This species has 

 previously been recorded from the West Indian region only. 



Amphinema turrida Mayer. 



Dissonema turrida Mayer, ; 00'', p. 44, pi. 2, i5gs. 3,4;: 04, p. 8, pi. 2, fig. 10. 

 Plate 7, fig. 2; Plate 40, fig. 6; Plate 43, fig. 3; Plate 44, figs. S, ^. 



Acapulco Harbor ; surface ; 4 specimens, the largest being 4 mm. in 

 diameter. 



Fortunately the specimens of this interesting species illustrate several 

 stages in the development of the gonads and show conclusively that they 

 belong primarily to the walls of the manubrium as already stated (p. 199), 

 and that their later outgrowth over the subumbrella surface is secondary. 



The general form has been well represented by Mayer (: 00'') ; the apical 

 projection is high and stiff, the bell walls very thin. The largest specimen 

 measures 3 mm. in diameter. 



Tentacles. — The two main tentacles are very stout, and rather longer 

 than the extreme height of the bell. The conformation of the rudimentary 

 tentacles separates this species very definitely from A. auslralis. The two 

 radial ones are of considerable size and length. Between the radial canals 

 in each quadrant there are three rudimentary tentacles (PI. 43, fig. 3), which, 

 according to the state of contraction, or possibly in part to individual varia- 

 tion, are either mere bulbs, or are prolonged into short filaments, as Mayer 

 figures them (: OO*"). I have observed both conditions in a single quadrant 

 of one specimen. Thus there are sixteen tentacular structures in all. On 

 the base of each of these, on its outer surface, there is an ectodermic ocellus 

 (PI. 43, fig. 3). 



The gonads of this species are its most interesting feature. In adult 

 specimens these structures appear, at first sight, to lie on the subumbrella 

 along the radial canals, as Mayer has represented them. It was this suppo- 

 sition which led him to include this species in the anthomedusan genus Dis- 

 sonema. Dissection shows, however, that in reality they likewise occupy the 

 walls of the manubrium. A study of the youngest medusa shows that they 

 originate on the manubrium, where they form eight thickenings (PI. 44, 



