20 THE VICTORIAN NATURALIST. 



constricted, sinus open and acute-angled ; semi-cells somewhat 

 narrowly pyramidate-truncate (more or less three-lobed) ; basal 

 part of semi-cells on each side sub-rectangular, each upper and 

 lower angle furnished with a short, 3-4-spinate process and 

 with a similar process arising from within the upper part of the 

 lateral margin ; upper two-thirds of lateral margins deeply 

 concave, apex convex but retuse in the middle, apical angles 

 furnished with a short 3-4-spinate process and with another 

 similar process arising within the apical margin close to each 

 angle ; with a shorter imarginate or 3-4-dentate process in the 

 centre of the lower part of the semi-cells, and often with one or 

 two dentate projections well within the concave portions of the 

 lateral margins. Vertical view elHptical, poles furnished with a 

 short spinate process, with a similar process on each side of the 

 polar one, and at the middle on each side with a shorter dentate 

 projection. Side view of semi-cell narrowly ovate-pyramidate, 

 with a sub-truncate apex ; disposition of processes shown clearly 

 in empty individuals. Cell wall punctate. 



Length with short processes 288-298 jjl, without processes 

 197-200 jj. ; breadth with short processes 163-178 /x, without 

 processes 134-153 fi ; breadth of apical part of semi-cell, 61-74 fi ; 

 breadth of isthmus, 35-46 fx. 



Habitat. — Cheltenham, Victoria ; abundant, 26th June, 1905. 



Note. ■ — This handsome species stands very near to X. 

 bi/urcatnm, Borge, but is more than twice as large, the apical 

 part of the semi-cells (the apical lobe) is much more produced 

 and outstanding, and the processes are proportionately very much 

 smaller and 2 -3-4-spinate (not bifurcate). X. bifoircatum was 

 described from Queensland, and, as the Victorian plant has such 

 distinctive characters, as its much smaller spinate processes 

 (which are not bificrcate) and the greatly produced apical lobe of 

 the semi-cells, it is belter regarded as a distinct species. 

 Moreover its dimensions are much greater than those of X. 

 bifurcatum — in fact, it is much the largest species of the genus yet 

 found. 



X. gloriosum exhibits certain irregularities with regard to the 

 disposition of its processes, more especially those at the apex of 

 the semi-cells. The normal number of apical processes is six, 

 one at each apical angle and two others on each side of it nearer 

 the middle. Sometimes there are two processes at each apical 

 angle, and then the two remaining ones are obliquely disposed. 

 In rarer instances, seven processes occur at the apex. The 

 central dentate wart is also variable, and is not infrequently 

 absent. 



COSMARIUM BIRETIFORME, G. S. WeSt (sp. n.) 



Of medium size, about as long as broad, or sometimes i}( 

 times longer than broad, deeply constricted, sinus very short or 



