HYDROZOA — RITCHIE. 851 * 



Diphasia sub-carinata, Bale, Cat. Austr. Hydroid Zoophytes, . 

 1884, p. 102, pi. iv., fig. 1, pi. xix., fig. 18. Id., Kirkpatrick, 

 Sci. Proc. Roy. Dublin Soc. (n.s.), vi., 18£0, p. 604. 



Station 54. 



The following observations supplement the accounts of Busk 

 and Bale. The hydrothecate lower portion of the stem is sepa- • 

 rated from the node-bearing portion by an articulation very 

 oblique in lateral view, and resembling from the front two cones, 

 the points of which interpenetrate. This type of node prevails - 

 throughout the colonies, but in the older portion of the stems 

 age has obliterated the definiteness of the structure. In the 

 hydrotheca, there is a very marked thickening of the abcauline 

 wall where it bends outwards, but the inner margin of the - 

 thickening is smoothly rounded and is not produced into a fine 

 ridge as in several species. The lateral ridge, on account of 

 "which the species has obtained its name, is due to a compression ' 

 of the free portion of the hydrotheca from above downwards, and 

 while appai-ent both on the anterior and posterior of the free - 

 part of the hydrotheca, it cannot, in these specimens, be detected 

 in the adnate portion. The general resemblance in structure - 

 between this species and Diphasia telraglochina, Billard, is very 

 marked, but a comparison of dimensions further emphasises the - 

 distinctness which Billard* ^ i-ecords. No trace of gonosome is - 

 present. 



Dimensions. — 



Height of colony up to 17 mm. 



Internode, length 0-74-0-80 mm. 



Hydrotheca, length adnate 049-0'52 „ 



free*3 0-33-0-36 „ 



,, diameter of lower portion 012-015 ,, 

 ,, „ at mouth 015-0-25 ,, 



Locality. — A small clump growing on Thidaria sinuosa from - 

 Station 54, within Jervis Bay; depth, 10 to 11 fathoms; 

 bottom, seaweed and sand ; 20th March, 1898. 



The species has been recorded only from Australian waters, 

 from Torres Strait to Bass Strait, at depths varying from 5^ to ~ 

 45 fathoms. 



Family PLUMULARID^. 



PLUMULARIA SETACEA (Linnaeus). 



Sertularia seiacea, Linnaeus, Syst. Nat., Ed. 10, 1758, p. 813. 



43 Billard -Arch. Zool. exper. (4), 1907, vii., pp.. 358, 359. 

 *3 To tip of lateral tooth. 



