396 



MEDUSA OF THE WORLD. 



Crossota brunnea Vanhoffen. 



Crossota brunnea, Vanhoffen, 1902, Wissen. Ergeb. deutsch. Tiefsee Expedition, Valdivia, Bd. 3, Lfg. I, p. 73, taf. 9, fign. 

 11-13; taf - I2 > fy. 11 - 34-38, 43-47.— Bigelow, H. B., 1909, Mem. Mus. Comp. Zool. at Harvard College, vol. 37, p. 135, 

 plates 2, 45. 



Bell dome-shaped, rounded, 32 mm. wide, 22 mm. high. Gelatinous substance fairly 

 thin, thickest at aboral pole of bell. 6 rows of small, solid tentacles arise from the bell-margin, 

 the entodermal, chordate roots of all of the tentacles arising from the radial-canal. The 

 younger tentacles arise between the older ones and at a lower level. There are thus 6 rows, 



Fig. 249. — Crossoia brunnea, after Vanhoffen, in deutsch. Tiefsee Expedition Valdivia. Showing insertions of tentacles 



at various levels above bell-margin. 



consisting of 84 tentacles, in each octant. 8 narrow, straight radial-canals. 8 sausage- 

 shaped gonads on the radial-canals near the stomach. Stomach small, 8-sided, with 4 lips. 

 No peduncle. Entodermal lamella and all entodermal parts are rich reddish-brown. Atlantic, 

 Pacific, and Indian Oceans; between the equator and 60° S. lat. at intermediate depths 

 down to 3,200 fathoms. Lithocyst-clubs (?) 



Crossota "norvegica" Vanhoffen. 



Crossota norvegica, Vanhoffen, 1902, Wissen. Ergeb. deutsch. Tiefsee Expedition, Dampfer Valdivia, Bd. 3, Lfg. 1, p. 75. 



Said to be characterized by its cherry-red color, instead of brown as in C. brunnea. Also, 

 the gonads in C. norvegica are more developed in small medusae than in specimens of C. 

 brunnea of the same size. Off the coast of Norway, at a depth of 500 fathoms. Briefly men- 

 tioned by Vanhoffen, to whom Dr. Hjost showed two specimens from lat. 69 13' N., long. 

 10° 40' E. As Bigelow states, this medusa is probably identical with Crossota brunnea. 



Subfamily AGLAURINjE. 



Circeadce (in part), Forbes, 1848, British Naked-eyed Medusae, p. 34. 



Aglauridx, Haeckel, 1879, Syst. der Medusen, p. 268.— Maas, 1905, Craspedoten Medusen der Siboga Expedition, Monog. 10, 



p. 57; 1906, Fauna Arctica, Bd. 4, Lfg. 3, p. 494, Jena; 1893, Ergeb. Plankton Exped., Bd. 2, K. c, p. 26.— Browne, 



1904, Fauna and Geog. Maldive and Laccadive Archipel., vol. 2, part 3, p. 739. 



SUBFAMILY CHARACTERS. 



Trachymedusae in which the stomach is mounted upon a gelatinous peduncle. With 8 

 radial-canals upon which the linear or sac-like gonads are developed. Numerous similar 

 tentacles and free sensory-clubs. 



The development of Aglaura is direct, without a fixed hydroid-stage, the actinula larva 

 being transformed directly into the medusa. The tentacles of the actinula become those of the 

 medusa and the bell is a secondary formation growing out in a collar-like expansion from the 

 sides of the body and carrying the tentacles outward. The lithocyst-clubs develop before the 

 bell and are evidently modified tentacles, the concretions being of entodermal formation. The 

 bell of Aglaura appears, therefore, to be not homologous with the bell of Anthomedusae and 

 Leptomedusae, for in these orders the bell forms before the tentacles and all of the tentacles 

 arise later from its margin, whereas in Aglaura many of the tentacles precede the bell and are 



