Avstrallan Hydro uh. 3 5 '3 



average about 2.5 iiiiii. in length, with the rachis straight and the 

 front arched, the rows of sarcothecae strongly oblique, and each 

 consisting of about six sarcothecae of some .148 mm. in length; 

 the colour rather dark red-brown. 



Aglaophknia BAKKKi, u. sp. (Plate XVII., Fig. 7-8). 



This species, which was collected at Western Port by Mr. F. H. 

 Baker, is an extremely close ally of A. sinuosa, of which it may 

 perhaps prove to be a variety. The structure as regards the stem 

 and branches is identical, but the hydrocladia are less divergent in 

 the present form than in A. s.>nuosa, where they stand off at a 

 rather Avide angle, with the two cauline sarcothecae in a line about 

 at right angles to the base of the hydrocladium, and therefore 

 diagonal to the stem-inter node. In A. baker.i these sarcothecae are 

 in a line very oblique to the hydrocladium, and much more nearly 

 parallel with the axis of the stem. 



In the number and form of the hydrotheca-teeth the two species 

 are nearly alike, but in A. sinuosa (as seen in exact profile) the 

 first tooth on each side appears narrow, the second and third wider 

 and nearer together, and the fourth very narrow; while in A, 

 hakerd the first looks wider, the second rather smaller, and the 

 third about as large as the first, the fourth being very minute or 

 obsolete. This description applies to typical hydrothecae, but the 

 characters are rather inconstant. 



There is a difference in the posterior intrathecal ridge, which 

 in A. sinuosa extends half through the hydrotheca, but in A. 

 baker/ is narroAver. But the most patent distinction is in the 

 lateral sarcothecae, which, as seen in the front view of A. sinuosa, 

 are very large and prominent, a feature not found in the present 

 species. 



Only two corbulae were observed, both on the same branch, and 

 the sex was not determinable. They are about 3 mm., in length, 

 and therefore somewhat lons:er than those of A. sinuosa, lighter 

 in colour, with about eleven pairs of leaflets. The rows of sar- 

 cothecae are less oblique than those of A. sinuosa, and the 

 sarcothecae themselves are smaller (about .104 mm.). In contrast 

 to the condition in A. sinuosa, wliere the fiont of the corbula is 

 regularly arched, so that it becomes gradually narrower towards 

 the ends, these corbulae are widest near the ends, and they are 

 somewhat constricted at two places near the middle, at which part 

 the form of the leaflets and the arrangement of the sarcothecae 

 become irregular. But possibly these peculiarities may be merely 

 abnormal. 



