A COLLFA'TION OF HYDI^OIDS. 321 



Diameter 0"081 mm.; thickness of perisarc 6 |/. 



Hy drocaulus. — Slender traiisjnirent stem divided into 

 short internodes, each carrying- a pinna on a process near 

 the middle. 



Pinna? alternate^ bearing a single hydrotheca ; there are 

 two internodes, a short proximal one, and a longer distal one 

 carrying the hydrotheca and projecting beyond it as a sharp 

 spine. 



Diameter of stem, about at the middle, 0"040 mm. ; thick- 

 ness of perisarc 5*6 ^<. 



Hydrotheca. — Eounded at base, much compressed later- 

 ally, aperture at right angles to the pimia, margin somewhat 

 everted. An intra-thecal ridge just below the aperture curves 

 forwards and downwards nearly to the base of the hydrotheca. 

 Nematophores bi-thalamic with slender bases, one below each 

 hydrotheca, one at each side above it, one in each axil, and 

 one at the lower part of each stem-internode. 



Width, measured from aperture along a line parallel to the 

 pinna, O'llo mm. ; height, measured at right angles to width 

 measurement, 0"lo7 nun. Nematocysts of the nematophores, 

 length 6'2 f^i; breadth 1*5 ^u. 



Hydranth. — About 13 tentacles; nematocysts not dis- 

 tinguished. 



GoxosoMES. — Clonangia unknown . 



Bale's hydroid was found at Queen's Cliif, S. Australia, 

 and the Natal hydroid agrees in all respects with his 

 description. 



(25) Kirchenpaueria mirabilis {Allman). 



DiPLOCHEiLUS MIRABILIS, Allman. 'Challenger Reports.' 

 Kirchenpaueria mirabilis {Allman). Bale, W. M., " Further 



Notes on Australian Hy- 

 droids," 'Proc. R. S. Victoria,* 

 1893, p. 1(»9. 



