SEMAEOSTOME^^PHACELLOPHORA. 



613 



GENERIC CHARACTERS. 



Ulmaridie with i6 marginal sense-organs and numerous marginal lappets. The ten- 

 tacles arise in l6 simple, linear clusters from the floor of the suhumhrella, centripetal to the 

 margin. Central mouth surrounded by 4 mouth-arms hearing curtain-like lips. CJonads 

 are 4 complexly folded sacs which project outward in the 4 interradii from the floor of the 

 subumbrella. No subgenital pits. The central stomach gives rise to numerous radiating 

 canals, some of which anastomose. There is a ring-canal at the bases of the marginal lappets. 

 Tentacles hollow. 



Synopsis of the Species of Phaccllophora. 



♦Intermediate in character between P. camtschatica and P. ornata. 

 ■j-Closely allied, probably identical. 



Phacellophora camtschatica Brandt. 



Phaccllophora camnchalica, Brandt, 1838, Mem. Acad. Sci. St. Petersbourg, tome 4, Sci. Nat., ser. 6, p. 366, taf. 8. — ."^GASSiz, .\., 

 1865, North Amer. Acal., p. 44. — Haeckel, 1880, Svst. der Medusen, p. 549. — VANHorrEN, 1906, Nordisches Plankton, 

 Nr. II, p. 58, fig. 13. 



Bell flat, 500 to 600 mm. wide. i6 marginal sense-organs each beneath a large, projecting, 

 covering scale, which is flanked by 2 narrow, rhopalar lappets, each about half as wide as the 

 covering-scale itself, ih wide, nearly semicircular, velar lappets, each cleft into 7 marginal 

 lappets. 16 crescent-shaped linear clusters of tentacles arise from subumbrella floor of velar 

 lappets; the convexities of these crescents are inward and their horns outward, and each 

 consists of 20 to 24 tentacles. Tentacles about as long as bell-radius. The 4 mouth-arms are 

 wide, tapering, and thick, and about 1.5 times as long as bell-radius; their lips are folded 

 in a curtam-like manner. There are 4 interradial, sac-like gonads with narrow, perradial inter- 

 spaces between them. The central stomach gives rise to 16 rhopalar canals which send out 

 lateral branches, and also to 80 (1; x 16) simple unbranched velar canals. There is a ring-canal 

 at the zone of the tentacles, on the outer margin of which there arise 7 blindly ending, simple 

 diverticula in each velar lappet and a trident-shaped branch in the radius of each sense-organ. 



Bell colorless to bluish, gonads reddish-brown, canals jellow, tentacles light-violet. 



This medusa ranges along the shores of the North Pacific from Kamtschatka to San 

 Francisco, California. It has not been figured since Mertens studied it. 



Phacellophora sicula Haeckel. 



Phacellophora camtschatica, Hertwic;, O. ind R., 1878, N'ervensyst. und Sinnesorgane Medusen, pp. 113, 114, laf. 9, fig. 15; 



taf. 10, fig. 16. — Haeckel, 1880, Syst. der Medusen, p. 551. 

 Phaccllophora ambigua, Kishinoiye, 1910, Journal College of Sci. Tokyo, vol. 27, art. 9, p. 21, I fig. 



The brothers Hertwig describe the marginal sense-organs of this exceedingly rare 

 medusa and give a very diagrammatic figure of a pan of the bell-margin. They were appar- 



