BY \Y. M. BALE. 765' 



hyclrothecse are smooth, or nearly so, and the constriction below 

 the aperture is absent or very slight on the outer side, while it is- 

 strongly marked on the inner, so that the terminal portion of the 

 hydrotheca has the aspect of being recurved towards the hydro- 

 caulus, an appearance which is strengthened by the outer marginal 

 tooth being longer than the other two. The hydrothecai in this 

 variety are proportionately longer than in the others. Both series 

 are strongly directed forwards, and when the pinnate form is fully 

 developed the hydropliyton bears a remarkable similarity to that 

 o2 S. neglecta, from which species it may be distinguished by the 

 pinnae being mostly alternate instead of sub-alternate, and being 

 giveu off below each hydrotheca on the pinnate part of the stem 

 instead of below every second one on each side, by the much 

 shorter marginal teeth ot the hydrotheca, and by the internal 

 teeth, also by the different gonangia. 



While it must be admitted that the arrangement of these 

 varieties under one species is not perfectly satisfactory, they appear 

 to run into each other by so many intermediate forms that I have 

 so far failed to find any distinct line of demarcation between 

 them. It is not improbable that *S'. indivisa will have to be 

 referred to the same species, and perhaps ;S'. solidula. All the 

 varieties possess teeth within the hydrotheca-margin, one within 

 each of the two upper sides, and either one or three within the 

 lower side. The hydrotheca often has two minute rod-like 

 thickenings of the |»erisarc about midway down, on oi)posite sides. 



Sertularella somdula, Bale. 

 (Plate XV., figs. 3-4). 

 A specimen from Bondi, with the ends of the hydrothecie curved 

 outwards rather more than those of the type form. 



Sertularella cylindrica, n.sp. 

 (Plate XVI., fig. 7). 

 Hydrocaiilus about half an inch in height, simple or slightly 

 blanched, divided by oblique Joints into internodes of moderate 



