606 THE AUSTRALIAN HYDROMEDUSjE, 



Locality : Port Jackson. 

 Season : April, July. 



51. GENUS MITROCOMIUM. Haeckel. 



Eucopinae with sixteen marginal vesicles and eight tentacles 

 (4 perradial and 4 interradial) ; marginal cirrhi between them. 

 Four Gonads along the Radial canals. No stalk to the stomach. 

 Polyp colonies unknown. The structure of the marginal vesicles 

 was studied by the brothers Hertwig (1.) 



205. MITROCOMIUM ANNAE. nov. sp. 

 Plate XXIX., fig. 58-60. 



Umbrella flat, resembling a low cone and not watch-glass 

 shaped. Twice as broad as high. Stomach globular, small, with 

 four interradial dark spots, connected with the Umbrella by a 

 narrow neck only, about a third as long as the height of the 

 Umbrella-cavity. Mouth with four extended membranous lips, 

 which have radial grooves but no other folds. Gonads oval, 

 close to the ring-canal, and joined to the radial canal by a narrow 

 neck. Eight tentacles, with globular basal bulbs 1| times as 

 long as the diameter of the Umbrella. On each side of the 

 tentacle-bulbs a small bunch of short cirrhi. Sixteen marginal 

 vesicles between the tentacle bulbs. No marginal bulges. A 

 black Ocellus on the abaxial side of each tentacle-bulb. Polyp 

 colonies unknown. I have named this species after my wife, 

 who discovered it in the " Auftrieb." 



Colour : Medusa colorless, Gonads pale greenish-yellow. Ento- 

 derm of stomach brown. Ocelli black. 



Size : Height of Umbrella, 2-5 mm. ; breadth, 5 mm. 



Ontogenesis unknown. 



Locality : Port Jackson, rare. I obtained only 5 adult speci- 

 mens during the autumn. 



Season : Autumn, April-June. 



(1) 0. und R. Hertwig. Das Nervensystem und die Sinnesorgajie der 

 Medusen. Seite 90. 



