320 a monograph op the australian sponges, 



Structure. 



Main radiating fibres are still more developed than in the fore- 

 going species. They have been formed appai'ently by local 

 thickenings of the originally uniform network, bat they are nearly 

 straight, broken and abruptly bent only hei^e and there, about 

 twice as thick as the other fibres, which are similar to those of 

 Aulena villosa (Plate XXXV., fig. 26.) These main fibres contain 

 no foreign bodies. They are very rai'e, about 6 mm. apart from 

 one another. They are not found in the villi. 



Geographical Distribution. 



East Coast of Australia, Port Denison, Queensland (Ramsay.) 



Bathmetrical Distribution. 

 Shallow water, to 20 metres. 



29. GENUS HALMOPSIS, (1) NOUM GENUS. 



Auleninse with secundary diaphragm lamellae in the vestibule 

 space, which consist like Aulena of a reticulate sponge structure. 

 The terminations of the fibres project, as in that genus beyond the 

 surface of the sponge forming villi. The skeleton consists of 

 radiating main fibres, w^hich are straight and completely filled with 

 foreign bodies and tangental, connecting fibres, which have a 

 diameter one-tenth that of the main fibres. 



These fibres are clear and contain no foreign bodies. 



This genus is intermediate between Aulena and Halme. Similar 

 to the first in the high development of its vestibule cavity and 

 similar to the second in the formation of the skeleton. 



67. SPECIES. 

 HALMOPSIS AUSTRALIS, NOVA SPECIES. 

 Only Auloplegmaforms have been observed. 



Shape and Size. 

 This sponge resembles Aulena villosa in outer appearance pretty 

 closely. The usual shape is that of a flattened sphere. The sponge 

 (1) Halmopsis= deceptively like Halme. 



