with Observations on Australian Hydroids. 109 



Description of Australian, Cape, and other Hy- 

 droida, mostly new, from the collection of miss 

 H. Gatty, by Professor Allman. 



(Journal of the Linnean Society, 1885.) 



The above paper (which was only received here after the 

 -completion of the foregoing observations) contains descrip- 

 tions and figures of many new species from various parts of 

 the worJd, including two for which Professor Allman has 

 established new genera. Of one of these genera, Gattya, I 

 have inserted a notice in its proper place among the Eleu- 

 theroplea ; the other, Thecocladium, belongs to the Sertu- 

 lariidse, and is distinguished from Thuiaria by the fact that 

 its branches spring from within hydrothecge. 



The Australian Hydroids which Professor Allman de- 

 scribes are for the most part new, but a few known forms 

 are re-described and figured. I append notes on two or 

 three of the species :— 



Sertularella trochocarpa, n. sp. — This species appears in 

 ■some respects intermediate between Sertularia and Sertu- 

 larella, if an important feature of the latter genus be, as I 

 have always considered it, the presence of a single hydro- 

 theca only on each internode of the ramuli, instead of one or 

 more pairs, as in Sertularia, or two unpaired series, as in 

 Thuiaria. S. trochocarpa has two hydro thec^ on each inter- 

 node, which are distinctly alternate ; its general aspect is 

 that of a Sertularella, and the gonothecse are ringed and 

 provided with a funnel-shaped mouth, as in some varieties 

 of >S^. Johnstoni and its allies. Two Australian species of 

 Sertularia have the gonothecee ringed, but in these cases the 

 summit is neither funnel-shaped nor toothed. 



In all the species of Sertularella which have been hitherto 

 well known and full}^ described, there is a single hydro theca 

 ■on each internode, except in the principal stems of some of 

 the branched species. 



Sertularia minima, Thompson. — From the relative posi- 

 tion of the teeth of the hydrotheca in Professor Allman's 

 figure it would appear to represent the back of the polypary. 

 This would account also for the calycles not being shown in 

 ■contact with each other, which is almost invariably their 

 actual condition in the front of the polypary, except in the 

 lowest pair or two. 



The adnate condition of the opposite hydrothecse would 

 bring this species, as well as most of our other Sertularige, 



