HYDROZOA RITCHIE. 857 



along what has been described as the basal portion of the mesial 

 sarcotheca, and turning aside where a hammer-like projection of 

 chitin partially blocks the direct passage, and marks the base 

 of the mesial nematophoie strictly speaking, enters the anterior 

 portion of the hydrotlieca. The base of the hydranth thus lies 

 at the base of the large anterior tooth, and the hydranth when 

 expanded must double round the free margin of the intrathecal 

 ridge and bend backwards again towards the month of the 

 hydrotlieca. 



A sarcostyle, which has passed unnoticed, issues from a median 

 pore in the internode wall, in the angle behind the hydrotlieca. 

 Although it is unprovided with a special sarcotheca, it is suffi- 

 ciently protected by the posterior portion of the hydrotheca, and 

 by two expansions of the inteinode of unique character, which, 

 on each side, rise above the node. The margin of these, curving 

 forwards and downwards, merges at last with the lateral wall of 

 the hydrotheca, almost opposite the issuing point of the supra- 

 calycine sarcostyle. Gonosome not present. 



Dimensions. — 



Hydroclade-bearing internode, length 106-l-78mm. 



„ „ diameter 0-29-0-38 „ 



Hydroclade internode, length 0"40-0"45 „ 



,, ,, diameter 0'16 ,, 



Hydrotheca, depth 0-22-0-25 „ 



,, diameter at mouth (lateral aspect) 0"25-0"28 ,, 



,, diameter at mouth (frontal aspect) 032-0'36 ,, 



Localities. — A fragment growing on the bare axis of an Isid 

 Alcyonarian from Station 36, off Botany Bay, one mile from 

 sliore ; depth, 23 to 20 fathoms; bottom, sand to rock; 11th 

 March, 1898. A few fragments of a colony from Station 48, off 

 Wollongong, seven to eight miles from shore ; depth, 55 to 56 

 fathoms; bottom, sand and mud to rock ; 18th March, 1898. 



HALICORNARIA FURCATA, Bale. 



(Plate Ixxxvi., figs. 2, 3.) 



Halicornaria fiircata, Bale, Cat, Anstr. Hydroid Zoophytes, 

 1884, p. 178, pi. xiii., fig. 3, pi. xvi., fig. 5. Id., Bale, Trans. 

 Roy. Soc. Vict., xxii., p. 101 (p. 29 of reprint), 



Stations 44 and 48. 



Only a few colonies of this species have been found, the largest 

 being a simple stem, 9 cm. high, another 7 '5 cm. high, with a 

 few dichotomously forked branches, and with long, anastomosed 



