Further Notes on Australian Hydroids. Ill 



hydrocladia is thickened at intervals to form those internal 

 transverse ridges which ai'e found in most species of Plumularia 

 and its allies. In viewing the hydrotheca in front the inner 

 boundary of the ridge presents a biconcave aspect, or it may be 

 nearly straight in the central portion, except for a distinct median 

 tooth or point. The hydrothecte are very transparent and 

 colourless, but (in this instance at least) they bear immersion in 

 Canada balsam without shrinkage of the wall-thickenings or 

 distortion of any kind, though the everted circular margins are of 

 such tenuity that they are scarcely ti-aceable in balsam unless 

 exactly in focus. 



The cauline sarcothecai are somewhat variable in number and 

 arrangement, but there appears to be always an erect conical 

 one in the axil of every hydrocladium, with two or three on the 

 front of each stem-internode, the latter being very much of the 

 same character as those in front of the hydrotheca?. I have had 

 for a long time some specimens collected by Dr. Haswell at 

 Griffiths' Point, which consisted only of the basal parts of the 

 stem with bunches of gonangia, and which I now identify as 

 belonging to this species by comparison with Mr. Wilson's 

 specimens. They have no sarcotheca? on the stem, but only 

 apertures ; it is quite possible, however, that sarcothecBe may 

 have ])een formei^ly present. 



The stem-internotles bear sometimes one, sometimes two liydro- 

 cladia, the longer ones being mostly found in the older parts of 

 the polypidom and the shorter ones nearer the summit ; they 

 are, however, sometimes interspersed. The species appears 

 normally monosiphonic, but the lower part is sometimes slightly 

 fascicle d. 



The gonangia, which have not been hitherto known, reach 

 about one-eighth of an inch in length, with a few very irregular 

 transverse undulations and no neck or marginal ring. 



KiRCHENPAUERIA PRODUCTA, Bale. 



Plumularia producta, Bale, Journ. Micr. Soc. Vict., Apr., 

 1882, p. 39, pi. XV., fig. 3; Catal. Aust. Hyd. Zooph., p. 133, 

 pi. x., fig. 4. 



Azygoplon producium, Bale, Proc. Lin. Soc. N.S.W., 2nd ser., 

 vol. iii., p. 774, pi. xix., figs. 1 to 5. 



