594 THE AUSTRALIAN HYDROMEDUS/E, 



190. PENNARIA ROSEA, nov. sp. 

 Plate XXIV., figs. 40-42. 



The Medusostyles are met with on the proximal Hydranths, 

 from 2-6 on each. They possess very large tentacular rudiments 

 which are about three times as long as broad, and traces of ocelli 

 can be detected at their base. The Umbrella is oval, slender, the 

 space between the large Manubrium and the Subumbrella is taken 

 up entii'ely by the genital products. In the Aquarium the 

 Medusostyles always drop off before they discharge their contents, 

 which latter action is performed apparently by contractions of the 

 Umbrella. The presence of a Subumbrellar circular muscle is 

 proved hereby. 



On each stem about 20 Pinnae, and from 4 to 6 Hydranths on 

 each Pinna. The Hydranths are stout, somewhat flask shaped, 

 with a long mouth. The capitate tentacles numerous (20-30), 

 short and thick ; the verticil of filiform arms consists of 30-40 

 tentacles. 



Colour : Perisarc of Hydrorhiza and stem black and intrans- 

 parent. Proximal end of Pinna likewise deeply coloured, distal 

 half light yellow and transparent. Hydranths and Medusostyles 

 intensely rose coloured. 



Size: Medusostyles, 2x1 mm. ; Hydranths, 2*5 mm. long and 

 1*5 thick. Stems attaining a height of 8 cm. Pinna, 9-15 mm. 

 long. 



Ontogenesis unknown. The first stages only of the development 

 of the ovum were observed. 



Locality: Port Jackson. Laminarian Zone, together with 

 Tubularia, not rare. 



Season: Medusostyles are produced in autumn. (May.) 



(1) W. Bale. Catalogue of the Australian Hydroid Zoophytes, p. 45- 



