598 THE AUSTRALIAN HYDROMEDUS.E, 



times as long as those in the oral circle. The former are generally 

 recurved S — shaped, which makes the Hydranths appear so graceful. 

 The oral tentacles are curved downwards. Between the two 

 verticils the much branched tentacular processes are inserted, which 

 bear the numerous Medusostyles, which appear like bunches of 

 grapes. They are however, carried erect, and are not suspended as 

 the Medusostyles of Tubularia indivisa for instance, although the 

 number of Medusostyles on each pi*ocess greatly exceeds that of 

 other Tubularia with erect Genital tentacles. The Medusostyles 

 are highly rudimentary and small They appear as simple ovoid 

 sacs. 



Colour: Tentacles white, stomach of Hydranth and Entoderm 

 of the genital tentacles rose-coloured. Perisarc of Hydrorhiza and 

 Hydrocaulus light yellow. 



Size : Hydranths (aboral tentacles), 7 mm. across and 5mm. 

 long. Hydrocauli 10-12 cm. 



Ontogenesis. The Actinulse are born with four tentacles. 



Locality : Port Jackson, Laminarian Zone, very common. 



Season : Medusostyles in May. 



Note. — I have kept Hydranths with young Medusostyles alive, 

 after they had dropped off the Hydrocaulus in consequence of being 

 put into an Acpiarium, for over a fortnight in a glass cylinder 

 closed at both ends with muslin and submerged in the sea, and I 

 obtained well developed Actinulse from several of these. A few 

 Actinulse settled in the glass tube, but they were killed and lost 

 by the repeated visitations to which the cylinder was subjected. 



44. GENUS TIBIANA. De Lamarck. 



Polyp colonies consisting of a Hydrocaulus from which stems 

 arise which bear Polyps laterally, alternate or rarely scattered. 



196. TIBIANA RAMOSA. De Lamarck. 



This species was described from Australia, by De Lamarck (1.) 



(1) Be Lamarck. Histoire Nat. des animaux sans Vertebres. Tom II , 

 p. 149. 



