328 EENEST WARREN. 



(1) Absence of intervening internodes not bearing hydro- 

 theca3 ; seen also in the aberrant Kirclienpaueria. 



(2) Hydrotliecfe face towards the front, instead of being 

 placed along the npper edge of the lateral branches. 



(3) Toothed margin of the hydrotheca. 



(4) The median nematophores above and below the hydro- 

 theca are fixed ; seen also in Kirclienpaueria. 



(27) Halicornaria segmentata s-p. )i. (PI. XLYIII, 



figs. 33-36.) 



This hydroid grows in an arborescent manner ; it is of a 

 dark brown or black colour, and reaches a height of about 

 3 inches. Only one specimen has been found ; it was attached 

 to the surface of the rock at the bottom of a deep pool at 

 some distance above the low-tide line. 



Trophosome. — Hydrorhiza forms a felt-work on the sur- 

 face of the rock, diameter very variable, average about 

 0*24 mm., thickness of perisarc about 32 /j. 



Hydro caul us. — Main stem shows a tendency to be 

 fascicled, especially towards the base, where lateral tubes are 

 given off, which grow downwards in contact with the parent 

 stem, and on arriving at the base branch out into an ordinary 

 hydrorhiza ; irregularly branched with pinnate stems. The 

 pinnate stems are faintly marked into internodes by indistinct 

 nodes. Pinnee alternate, and sharply divided into internodes 

 by oblique nodes ; on the posterior face of the pinna3 the 

 internodes are prolonged forwards into a sharp ridge, which 

 on side view makes the pinna very obviously segmented 

 (PI. XLYIII, fig. 33). 



Nematophores : The mesial nematophore long and broad, 

 aduate to the hydrotheca nearly to the marginal spine 

 (fig. 33, 6-2)i.). Lateral or supra-calycine nematophores large 

 and cylindrical. The pinnate stems are provided with cup- 

 shaped nematophores, somewhat irregularly placed ; there 

 appear to be usually three around the base of the pinna, and 



