50 "ENDEAVOUR'' sciKvnnc RESULTS. 



middle, everted horizontally, and a less pronounced lobe further 

 back ; back of hydrotheca free, more elevated than the front, so 

 that the aperture is oblique ; the aperture into the hydrocladium 

 with two or three minute denticles on the margin. No septal 

 ridges in the internode. 



Mesial sareotheca? as long as the hydrothecas or longer, free for 

 more than half their length, the free part diverging Avidely from 

 the hydrotheca and overhanging its aperture ; free portion some- 

 times single but more often dividing into two distinct tubular 

 branches, which diverge widely from each other laterally ; ter- 

 minal apertures small, lateral aperture large, adjoining the hydro- 

 theca. Lateral sarcothecse saccate, adnate, with a small tubular 

 aperture directed forwards and outwards, distinct from the wide 

 lateral aperture. Cauline earcotnecse similar to the laterals, 

 two on the rachis at the base of each hydrocladium, and a third 

 at the back of each axil. 



Gonotheca? about three times the length of the hydrotheca^, 

 campanulate, truncate, membranous, springing from the bases 

 of the hydrocladia. 



Colour. Light fawn, stems darker. 



The specimens comprised numerous shoots, all unbranched, and 

 are to the naked eye indistinguishable from H. urceolifera, 

 which is also found on A. megalocarpa. In the form of the 

 hydrotheca? and the mesial sarcothecee it is quite distinct from all 

 the known Australian species, but it has the characters, common 

 to all of them, of the monosiphonic habit, the absence of septal 

 ridges in the interuode, the sarcotheca^ at the back of the axils, 

 and the denticles on the margin of the opening from the inter- 

 node to the hydrotheca, which, by analogy with sarcopore, might 

 be termed hydropore. 



The most striking characteristic of the species consists in the 

 bifurcated mesial sarcotheca-. There is much variation in these 

 appendages, some only forking close to the ends, others much 

 further back, and many remaining simple. As a rule those near 

 the two extremities of the hydrocladia are the less developed. 

 The lateral sarcothecee have the tubular mouth longer and 

 directed more forward as they approach the ends of the hydro- 

 cladia ; a condition found also in many other species. 



The position of the intrathecal ridge, between the hydrotheca- 

 lip and the mesial sarcotheca, has not been observed in any 

 Australian species described hitherto, though common in 

 AglaopJienia and Lytocnrpus. The oblique aperture of the 



