488 MEDUSA OF THE WORLD. 



Sarsia coccometra Bigelow. 

 Sarsia coccometra, Bigelow, H.B., 1909, Mem. Mus. Comp. Zool. at Harvard College, vol. 37, p. 179, plates 7, 40, and 43. 



Bell 5 mm. high, 4 mm. wide, with thin walls and pointed apex. 4 tentacles twice as 

 long as bell-height and ringed with prominent nematocyst swellings. The outer end of each 

 tentacle is swollen, knob-like, and covered with nematocysts. The tentacle-bulbs are swollen 

 and each has a black, abaxial ocellus. 4 slender radial-canals and a short axial canal above 

 the stomach. Manubrium as long as depth of bell-cavity and entirely encircled by the gonad, 

 leaving only the short throat-tube free. The eggs are very large. .Gonads reddish and tentacle- 

 bulbs Vandyke-brown. Pacific coast of Central America. 



This form somewhat resembles Sarsia cximia of the Atlantic, California, and Alaskan 

 waters, but appears to be distinguished by its apical projection, axial canal, and knobbed 

 tentacles. 



Syncoryne sarsii (see page 52). 



Syncoryne sarsi, Goette, 1907, Zeit. fiir wissen. Zool., Bd. 87, p. 35, taf. 4. 



Goette gives a detailed account of the development of the medusa-buds. The sperm 

 originates and remains in the ectoderm, but the egg-cells originate in the entoderm of the 

 stomach-region of the spadix and afterwards migrate into the ectoderm. 



Sarsia pulchella (see page 57). 



Sarsia pulchella, Hartlaub, 1907, Nordisches Plankton, Craspedote Medusen, p. 109, I fig. 



Hartlaub figures a twin monster of Sarsia with two bell-margins. The bell cavities appear 

 to be connected by a transverse canal, but the two gastrovascular systems are separate. Double 

 monsters have been seen in Bouganivillia caroltnensis and Pseudoclytia pentata. 



Ectopleura dumortieri (see page 69). 

 Ectopleura ochracea, Bigelow, H. B., 1909, Mem. Mus. Comp. Zool. at Harvard College, vol. 37, p. 184, plates 6 and 38. 



Bigelow found many specimens of this medusa in Acapulco Harbor, Pacific coast of 

 Mexico. It appears to be identical with E. ochracea of the southern coast of New England, 

 and this form I was unable to distinguish from E. dumortieri which I found in the English 

 Channel in 1907. 



Genus Moerisia Boulenger, 1908. 



Marina, Boulenger, 1908, Quarterly Journal Microscop. Science, vol. 52, p. 358. 



The type species is Moerisia lyonsi Boulenger, from the brackish Lake Ourun which 

 communicates with the Nile in the Fayum province of Egypt. 



The medusa resembles Sarsia but the jronad extends outward from the sides of the stomach 

 along the 4 radial-canals. The hydroid has a single circlet of holloiv tentacles and produces 

 medusa-buds and asexual planula-like buds upon the sides of the hydranths. 



The hydroid resembles Hydra and departs from all other hydroids in having hollow 

 tentacles. 



Moerisia lyonsi Boulenger. 



Mccrisia lyonsi, Boulenger, 1908, Quarterly Journal Microscop. Science, New Set., vol. 52, p. 357, plates 22,23; T 9°9» Proc. 

 Cambridge Philosoph. Soc, vol. 15, p. 180 (migrations of nettling-cells). 



This interesting medusa and its hydroid are described in detail by Boulenger from the 

 brackish lake Ourun, the remains of the historic Lake Mceris which was in ancient times used 

 as an artificial regulator of the Nile. It is in the Fayum province of Egypt, and it is probable 

 that this medusa is a survivor of the fauna of the Pliocene sea which once covered the Fayum 

 depression. . j 



The medusa resembles Sarsia but the gonads extend outward from the stomach-walls 

 along the 4 radial-canals. Bell globular, thick-walled, 4.5 mm. wide and about 4 mm. high. 



