BY W. M. BALE. 791 



sarcothecse canaliculate, abruptly curved outwards, projecting 

 forwards about as far as the margin of the hydrotbeca. Cauline 

 sarcothecse broad, canaliculate, two on the front of the stem at the 

 base of each pinua, and a large one, usually bifid, behind each axil. 



Gonangial pinna bearing a single hydrotheca below the corbula. 

 Corbula consisting of about 10 pairs of alternate ribs, each springing 

 from a separate internode of the rachis, expanded into I'ather 

 narrow leaflets, which are united to each other so as to form a 

 closed corbula ; the lines of union of the leaflets indicated by 

 narrow thickened ridges (without sarcothecae), a median ridge 

 running up each leaflet bearing a series of canaliculate sarcothecse; 

 the median ridge often united to the next junction-ridge behind 

 by a few irregular short thickenings ; a bifid sarcotheca on the 

 basal part of each leaflet, situated between the median ridge and 

 the distal margin ; one (or two ?) sarcothecse on the rachis at the 

 base of each leaflet. 



Colour, brown. 



Hah. — Port Denison. 



The largest specimen I received was about 1^ inches long, with 

 a single branch near the foot. The species may be readily 

 distinguished by the structure of the hydrotliecse, which are 

 peculiar in having both the anterior and posterior intrathecal 

 ridges fully developed, and forming two partitions, each projecting 

 half-way through the hydrotheca, but in opposite directions, The 

 keel which extends along the front of the hydrotheca is also an 

 unusual feature. The corbula is completely closed, and the leaflets 

 which com])Ose it are narrower than is usual in closed corbulse, so 

 that the rows oi sarcothecie are closer together, while their position 

 is along the middle of each leaflet, not as is generally the case 

 at the margin. 



Aglaophenia macrocahpa, i\.sp. 

 (Plate XXL, figs. 3-4). 

 Hydrocaulus polysiphonic, with divergent branches, stem and 

 main branches thick and woody, pinnae approximate, alternate, 



