SEMAEOSTOME^ — DISCOMEDUSA. 



()()7 



24 and 32 to 40 and 48, respectively. Thus Discotncdiisa is a growth-stage in the development 

 of Undosa. The medusa of Trieste, Adriatic, appears to become mature, however, with 

 only 24 tentacles, and it is interesting to observe that under unfavorable conditions in brackish 

 water Dactylometra also becomes mature with 24 instead of 40 tentacles. 



taculae. Mouth cruciform. 



Discomedusa lobata Claus. 



(?) Medusa slelligrra Ehrf.nbf.rc;, 1S35, Abhandl. Acad. Berlin, p. 260. — 1836, Akalcphcn des Rothon Mccres, p. 82. 

 Discomedusa lohata, Claus, 1877, Denkschr. Wicn. Acad., Bd. 38, p. 42, taf. 8, 9. — Grafh-k, 18S4, Arbrit. Zool. Inst. Wicn., 



Bd.5, p.343. 

 Vmbrosa lobata, Haeckel, 1880, Syst. der Medusen, p. 546. 

 Ulmarls prolotypus {> young medusa), Haeckel, 1880, he. cli., p. 545, t.if. 33, fign. 1-4. 



Bell shield-shaped, flatter than a hemisphere, 150 mm. wide, 40 mm. high. The 16 

 ocular lappets are as wide as, but somewhat longer than, the 16 tentacular lap|)ets. There 

 are 24 tentacles, and 8 adradial ones are about as long as bell-diameter and twice as long 

 and thick as the 16 secondar)- tentacles. The 4 mouth-arms are wide, tapering, somewhat 

 longer than bell-radius and with curtain-like, folded margins provided with numerous ten- 

 Genital radius somewhat wider than half the bell-radius. The 4 

 crescentic gonads are convex outwardly 

 and their ends nearly touch in the 4 per- 

 radii. Centripetal to these gonads are 4 

 lines of long, numerous, gastric cirri, one 

 row for each gonad. 



The central stomach gives rise to 8 

 unbranched, adradial canals and to 8 per- 

 radial and interradial vessels, each of 

 which gives rise to a pair of branched 

 and anastomosing side-branches, the ter- 

 minal ramifications of which fuse with the 

 adradial canals and with the marginal 

 ring-canal. 



This medusa is found at Trieste, Adri- 

 atic Sea, from December to March, the 

 3'oung being common in January and the 

 adult in February and March. Claus gives 

 the best description of it. It may be iden- 

 tical with the imperfectly describedil/^(/;«rt 

 stelligera Ehrenberg, from the harbor of 

 Alexandria, Egypt, in October. Ehren- 

 berg's medusa, however, appears to have 

 about 40 short tentacles, all of equal 

 length, and may therefore belong to Haeckel's genus Undosa. 



The young medusa oi Discomedusa lohata passes through a stage wherein there are only 

 16 lappets and 8 adradial tentacles. The 8 adradial canals are simple and the 8 perradial 

 and interradial ones branched. 



Discomedusa philippina, sp. nov. 



This form is allied to D. lobata of the Mediterranean, but it appears to be smaller and to 

 differ in the bluntness of its lappets, in having no fusions between the adradial and perradial 

 and interradial canals, and above all by the blind branches on the outer side of the ring- 

 canal. 



Bell 29 mm. wide, flatter than a hemisphere, evenly rounded, exumbrella thickly be- 

 sprinkled with prominent wart-like projections. Gelatinous substance tairly thick at center, 

 thin at bell-margin. 8 rhopalia. 32 oval lappets all similar each to each, thus differing from 

 D. lobata. 24 tentacles, the 8 adradial being longer and stouter than the 16 intermediate ten- 

 tacles. The tentacles were all broken oft" in the specimens obtained by the Albatross so that 

 their lengths could not be determined. 4 simple, crenulated lips at the end of a 4-corncicd 



Fig. 387. — ^^Ulmarls protot\pus" after Haeckel, in 

 Das Syst. der Medusen. 



