AUSTRALIAN HYDROMEDUS.E. 21 



12. Genus IDIA. Lamouroux. 



Colonies pinnately branched. The trophosomes form two continuous series 

 in contact with each other along the front of the stem. 



39. Idia pristis. Lamouroux. (9) 113, (83) 200, (84) pi. V., fig. 5 (85) 



462, (93) 419. 



Sertularia pristis. (18) 390. 



North coast of Australia (Torres Straits), east coast of Australia (Fitzroy 

 Islands, Albany Passage). 



13. Genus THUI ARIA. Fleming.* 



Trophosomes biserial, not in pairs, usually more or less immersed. The 

 series differently dense. 



40. Thuiaria fenestrata. Bale. (9) 116, (93) 420. 



Salacia tetrocytharia (83) 214, (84), g. pi. 15, (85) 673. 

 Sertularia, crisioides (18) 389. 



North coast of Australia (Torres Straits), east coast of Australia (Albany 

 Passage). 



41. Thuiaria quadrldens. Bale. (9) 119, (93) 420, (98). 



East coast of Australia (Port Curtis, Holborn Island), New Zealand. 



42. Thuiaria lata. Bale. (8) 26, (9) 120, (93) 420. 



East coast of Australia (Port Stephens), south coast of Australia (Port 

 Phillip, Western Port). 



VI . Familia RHABDOPHORA. 



Allman, 1872. 



Possessing a chitinous endo and exo-skeleton ; the former rod-shaped ; 

 colonies free swimming ; probably extinct. 



I. GROUP. GRAPTOLOIDEA. 



Lapworth. 



Hydrosome developed from a sicula, every canal containing coenosarc, bears 

 only one row of cells. Axis (virgula) on the dorsal side in a furrow of the 

 inner lamina. 



A-MONOPRIONID^]. 



Hydrothecse in one row opposite the axis. 



I._Sub-familia MONOGRAPTINJE. V. Lendenfeld. 

 = MONOGRAPTIDJE. Lapworth. 



Developed one-sided ; pointed ends of the sicula pointing upwards, united 

 with the dorsal margin of the proximal end of a single or composite hydro- 

 some. 



* I had no opportunity to examine sufficiently well preserved gonophores of Thuiaria. 

 It appears highly probable that this genus belongs to the Hydromedusinse. 



