Boone, Coelenterata, Cruises of "Eagle" and "Ara," 1921-28 47 



1881.— Archer, H'., ibid, p. 307.— Haeckel, Syst. der Medusen, 

 p. 568, 1880; Report Voy. "Challenger," ZooL, vol. 4, p. 118, 1881. 

 — Vanhoffen, Bibliotheca Zoologica, Bd. I, Heft, 3, p. 40, 1888. — 

 Bigelow, R. P., Johns Hopkins Univ. Circ., vol. 2, no. 106, p. 106, 

 1893. — Perkins, Yearbook, Carnegie Inst. Washington, no. 4, 

 p. 15, 1906 ; Publ. 102, Carnegie Inst. Washington, p. 152, 1908.— 

 Mayer, A. G., Medusae of the World, vol. Ill, p. 647, pi. 69, 

 figs. 1-3, pi. 72, upper three figs., color plate, 1910. 



Rhizostommata Dichtoma Vanhoffen. 



Genus : COTYLORHIZA L. Agassiz. 



Cotylorhiza tuberculata (Macri). 



Plate 9. 



Type : Collected in the Mediterranean Sea ; depository not traced. 



Distribution: This species is found chiefly in the Mediterranean 

 Sea, but has also been found in the Atlantic Ocean near the Canary 

 Islands. There is one valid record of its occurrence in the Red Sea, 

 where it is believed to have been introduced via the Suez Canal. 

 Pelagic. This species varies considerably in abundance, sometimes 

 being very rare, especially so in midwinter. It is believed by Keller 

 to be a deep water species which only comes to the surface occasionally 

 when sexually mature and that the young remain at the bottom of 

 the sea. 



Material examined: One very large specimen, Monaco Harbor, 

 1927. 



Color : The bell is rich olive tending to orange or brownish yellow, 

 being darker brown on the dome-like apex of the exumbrella. Both 

 the exumbrella and subumbrella show a rich yellow color due to the 

 presence of multitudes of yellow and brown plant cells (Zoochlorellae) 

 which are present in the canal system and entoderm. The mouth-arms 

 and disk are milky white tinged with creamy yellow; the free outer 

 margins of the mouths are purple varying to violet or deep blue as 

 are also the terminal parts of the milky white appendages. (See also 

 Mayer's color plate.). 



Life history : Much careful study has been made of the life history 

 of this species by Busch, Frantzius, Gegenbaur, Kowalevsky, Claus, 

 Goetle, du Plessis, Hein, Mayer and others. 



Technical description : Consult Mayer, 1910, vol. Ill, p. 659, for 

 an excellent modern description of this species. 



