with Observations on Australian Hydroids. 101 



Halicornaria fuecata, Bale. 



The remarks in the " Catalogue" respecting this species 

 might lead to the supposition that the axillary hydro thecse 

 are borne directly on the stem, but this is not the case. 

 Where the stem bifurcates a single hydrotheca usually pro- 

 jects from tlie axil, but it is supported by a true hydro- 

 cladium, which, however, consists of a single internode 

 only. 



Halicoenopsis avicularis, Kirch. 



Azygoplon rostratum of the " Challenger" Report is the 

 same as the species which I have described under the 

 above name^ and I have no doubt of the specific identity 

 of Kirchenpauer's Aglaoj^henia avicularis, though Pro- 

 fessor Allman is not satisfied on this point, owing to an 

 apparent difference in the mesial sarcotheca ; a difference, 

 however, which seems to me to depend merely on a slight 

 inaccuracy in Kirchenpauer's figure, principally in making 

 the sarcothecse appear tubular. The interruption between 

 the upper and lower parts of the sarcotheca is often much 

 less conspicuous than in Allman's figure, and doubtless it was 

 a specimen in this condition which was figured by Kirchen- 

 pauer (as also by myself in the " Catalogue"). 



I have erroneously described this species as monosiphonic, 

 fan error into which Professor Allman has also fallen), it 

 being in reality polysiphonic, as described by Kirchenpauer. 

 The mistake is easily explained by the fact that the fascicled 

 structure only extends to the lower part of the stem and the 

 larger branches, so that all the smaller branches and the 

 distal portions of the larger ones (and in young specimens, 

 such as I had principally examined, the whole hydrophyton) 

 are really monosi phonic. The species is, moreover, more 

 closely allied to those which are monosiphonic in habit than 

 to the ordinary fascicled forms, since the branches spring- 

 directly from the internodes of the stout jointed stem or 

 larger branches, and not, as in those species, from the supple- 

 mentary tubes which are added to them. Each branch has 

 its origin at the side of the stem or larger branch, immedi- 

 ately opposite a hydrociadium. 



