A COLLECTION OF HYDEOIDS. 



303 



(15) Sertuliiria acantliostoma Bale. (PI. XLYI, figs. 



23-26.) 



Sertularia acanthostoma Bale, ' Catalogue of the Australian 



Hydvoid Zoophytes, 188-i, p. 85. 



There is probably Httle doubt that the Natal hydroid is 

 Balers acanthostoma; but, uevertheless, there are cei'tain 

 differences. 



Text-fig. 7. 



Sertularia acanthostoma Eale. 



The pinnate shoots reach a height of about 2 in. ; the 

 hydroid is straw-coloured, and grows attached to rocks near 

 the low-water line. Two small colonies only have been 

 found. 



Tkophosome. — Hydrorhiza consists of a branching, loose 

 reticulum. 



Diameter 0*101 mm. ; thickness of perisarc 10 //. 



Hydro caul us. — Pinnate shoots, pinnae slender at their 

 origin, opposite. Typically there are three pairs of hydro- 



