SEMAEOSTOME.E DIPLUL.M AIMS, S'l H I : \( i\] A . 611 



of side branches and thus 96 canals radiate outward toward the margin, before reaching 

 which they are all connected by a network of anastomosing vessels. There are 4 lips and 4 

 gonads. 9 ephyrs and young medusae of this species were found by the German Antarctic 

 Expedition between January and March. They ranged from 4 to 22 mm. in diameter. The 

 species appears to be quite variable, for only 6 of them were i6-raved, while the 3 others were 

 12, 15, and 17 rayed respectively. 



Two immature specimens were studied by Maas. The bell of larger was 35 to 40 mm. 

 wide. 16 marginal sense-organs flanked by only 32 bluntly-pointed lappets. 16 hollow, 

 tapering tentacles, somewhat shorter than the bell-radius. These tentacles arise from the 

 inter-rhopalar clefts between the lappets. The rhopalar clefts are only halt as deep as the 

 inter-rhopalar. Ventral stomach circular, nearly as wide as bell-radius. 16 trident-shaped 

 radial-canals arise from the stomach-margin in the rhopalar radii and alternate with 16 

 straight, narrower, unforked canals in the tentacular radii. All the radial-canals give off 

 anastomosing side branches in the outer parts of their lengths near the ring-canal. The ring- 

 canal is at the zone of the origins of the tentacles, and 16 slightly branched radiating diverti- 

 cula extend outward from it to the sense-organs. The 4 lips are bordered by curtain-like 

 fringes. 4 interradial gonads with clusters of gastric cirri. Canal system yellowish-brown, 

 the tentacles dull purple. The specimen was immature. 



Maas also describes a smaller specimen only 15 mm. in diameter (fig. 390). This had 

 8 long tentacles alternating with 8 short. The short tentacles project from the floor of the 

 subumbrella at some distance inward from the clefts between the lappets, and it appears that 

 during growth the clefts extend inward until they meet the tentacles at the zone of the ring- 

 canal. There are 16 simple, unbranched radial-canals in the radii of the tentacles and 16 

 trident-like canals in the rhopalar radii. None of these canals gives oft" side-branches close 

 to the ring-canal, as in later life. 4 interradial oval gonads are now visible, and the short 

 throat-tube expands into 4 pointed lips with folded margins. Central stomach circular, 

 about as wide as bell-radius. 



This medusa is found in the Antarctic Ocean from January to March where it lives 

 along the edge of the Antarctic continent having been taken at Cape Adare, off Kaiser \Yilhelm 

 II Land, and at other places. 



Subfamily STHENONINJE. 

 SUBFAMILY CHARACTERS. 



The tentacles arise in linear clusters from the floor of the subumbrella. 8 to 16 marginal 

 sense-organs. 4 protrusive, bag-like gonads without subgenital pits. 4 unbranched mouth- 

 arms. Some single and some branched radial-canals. 



Genus STHENONIA Eschscholtz, 1829. 



Sthenonia, ESCHSCHOLTZ, 1829, Syst. dcr Acalephen, p. 59. HATCKU, 1880, Syst. dcr Meduscn, p. 548. VANHOFFFN, 1906, 

 Nnrdisches Plankton, Nr. n, p. 56. 



The type species and only known form is Sthenonia albida of Awatscha Bay, coast of 

 Kamtschatka. 



GENERIC CHARACTERS. 



Ulmaridas with 8 rhopalia, 16 ocular lappets, 8 bifurcated velar lappets, and 8 adradial 

 clusters of tentacles which arise from the subumbrella. 8 branched radial-canals in the rho- 

 palar radii. Numerous simple or branched radial-canals in the radii of the velar lappets and a 

 ring-canal. No subgenital pits. 



Sthenonia albida Eschscholtz. 



Sihtnonia albida, ESCHSCHOLTZ, 1829, Syst. der Acalephen, p. 59, taf. 4. DE BLAINVIU.F., 1834, Man. d'Actinolope, p. 291, planche 

 36, fig. i. HAECVEL, 1880, Syst. tier Malusen, p. 548. VANH.I> > > N. 1C., i.joh, V.r.lisches Plankton, Nr. II, p. 56, fig. Z, 



This form has not been seen since Eschscholtz described it. 



Bell about 300 mm. wide, flat, and shield-shaped. 8 marginal sense-organs. 16 ocular 

 and 8 velar lappets with evenly rounded, reentrant markings. Each ocular lappet has a small 

 pointed projection into which the gastrovascular system extends, and each velar lappet has 



