HYDROZOA — RITCHIE. 859 



■described by Bale (1884). The colonies are iinbranched. The 

 hydroclades, two on an internode, are sub opposite, and arise 

 from opposite sides of the internodes, so that they lie in one 

 plane. The hydrothecje are deeper, their long axis is more 

 nearly parallel to tliat of the internode, and the aperture, there- 

 fore, faces more directly upwards. There is much variation in 

 the prominence of the marginal teeth, which are in some cases 

 almost obsolete, and which are never so prominent in anterior 

 view as are those portrayed in Bale's figure (1884, pi. xvi., fig. 

 .10). The margin, from the anterior aspect, seems to be almost 

 •cii'cular. The mesial sarcothecse are much shorter than those 

 described by Bale, some failing to outreach the anterior hydro- 

 thecal tooth, although some, for there is much vax'iation, overtop 

 it for a considerable distance. In this character, our specimens 

 appear to resemble those originally described by Bale (1882, see 

 1884, p. 184). 



In other respects the specimens agree with Bale's description. 

 I would add that on the first hydrotbeca of each hydroclade, the 

 mesial sarcotheca is distinctive, for it usually terminates, short 

 of the margin of the hydrotheca, in a broad free lip which lies 

 parallel to the anterior wall of the hydrotheca — the elemental 

 type of sarcotheca from which, as can be seen in these specimens, 

 tubular mesial sarcothecse and tubular supracalycine sarcothecse 

 have developed. 



DimeiisiotLS. — 

 Stem internode, length O'57-0-6O mm. 



,, ,, diameter 0-45-0-54 ,, 



Hydroclade internode, length 0-26-0-31 „ 



,, ,, diameter 014-018 ,, 



Hydrotheca, depth 0-21-0-22 ,, 



,, breadth at mouth (lateral aspect)... 0-16 ,, 

 ,, length of free portion of mesial sar- 

 cotheca 005-0-13 ,, 



Oauline sarcotheca, greatest width O'll ,, 



Locality. — Southern coast of New South Wales. 



The species is confined to the waters of South and East 

 Australia. 



HALICORNARIA THETIDIS,*^ sp. nov. 

 (Plate Ixxxv., fig. 1 ; Plate Ixxxix., figs. 3, 4.) 



Stations 44 and 48. 



Trophosome. — Two simply pinnate, unbranched, unfascicled 

 colonies, the largest of which is 18 cm. high, were found at 



4» Named in honour of H.M.C.S. "Thetis." 



