Australian Hydroids. 339 



as a varietal form of »S'. lata; these agree so completely with my 

 present specimens that I have now little doubt that they really 

 belong to the same species. Of course if it should be found that 

 the trophosomes of either or both species intergrade so far as to 

 bridge the slight gap between them it will have to be recognised 

 that certain identification will be possible only in the presence of 

 *he gonangia. 



Whether the species l^efore us is really the S. tride-ntata of 

 Lamouroux is doubtful. The figure published by Billard in 1907 

 as S. lata undoubtedly belongs to the present species, but unfor- 

 itunately Billard did not give a figure of Lamouroux' specimen in 

 -his revision of that author's collection; he mentions, however, that 

 the hydrothecae were as closely set as in my figure of ^S'. lata, a 

 •character which would tend to indicate that Lamouroux' specimens 

 may belong to the true S. lata, or else that they may be, as to the 

 -trophosome, intermediate. If they are not sufficiently distinctive 

 i:o be referred with certainty (the gonosome being absent) to either 

 form they should be ignored; in any case unless they can be clearly 

 identified with' the present species the name of S. diaphana 

 '(Allman) must remain. 



I follow Billard in associating *S'. Torreyi Nutting with his " *S'. 

 tridtntata,'' and I find nothing to distinguish S. speciosa 

 Congdon from Nutting's species. T. diaphana Allman has also 

 Jbeen associated with these by Billard, in this case after examining 

 the original type. The gonangia were observed in all these forms. 

 Allman's types of T. hyalina, in which the gonosome was wanting, 

 have been examined by Billard and also by Nutting, who both 

 considered the species the same as the present. Neither of these 

 -observers refers to the hydranths of T. hyalina, regarding which 

 Allman says that the hydranth is quite unable, even when most 

 fully retracted, to withdraw the tentacular crown into the hydro- 

 theca, and that notwithstanding the complete development of tlie 

 latter the hydranths derive almost as little protection from them 

 as those of Jlalecium do from the hydrotliecae in tliat genus. This 

 description is not applicable to S. lata, as I have a specimen 

 Including the hydranths, which are fully retracted into the hydro- 

 thecae, anf) with ample space to spare. Congdon has observed the 

 hydranths in his *S'. s^peciofia, and has figured them expanded, but 

 says nothing as to tlieii- reti-actility. 



