20 Transactions. — Botany. 



front-view sub-semicircular, basal angles slightly rounded ; 

 edges incised with numerous (eighteen to twenty on each) 

 crenulations, of wdiich the little elevations are truncate ; 

 cytioderm apparently slightly grooved just within the edge ; 

 in the centre of each segment a circular granuliferous infla- 

 tion, the granules arranged more or less concentrically, and 

 connected by a network of fine rays ; between the inflation 

 and the edge are three concentric rows of granules. End- 

 view elliptical, the edges crenulate, the median inflation 

 conspicuous, sub-orbicular ; on the surface are six rows of 

 granules, arranged longitudinally. 



Long., 50jit ; lat., 33-36 p. ; crass., 18 /x ex. inflat. 



Eutherford's Swamp, Otaki. 



This handsome plant is apparently an intermediate form 

 between the original C. qnodrifariuvi- and its varieties hexasti- 

 chum, Lundell, and octastichuni, Nordstedt. From the for- 

 mer it differs in having six rows of granules in end-view instead 

 of four, and from the two latter in having the granules on the 

 median inflation arranged more or less concentrically instead 

 of in direct rows. The network of rays connecting these 

 granules appears to be a character visible in the var. octasti- 

 chiim. The edges in end-view in my specimens do not 

 exhibit such conspicuous " papilke " as those figured by 

 Lundell and Wolle, Ijut have obscure crenulations. I have 

 not seen the zygospore, which in G. qiiadrifarmm is quadrate, 

 a rather unusual form amongst Cosmaria. 



Genus Xanthidium, Ehrenberg. 

 Xantliidiwni intermedium, sp. nov. Plate IV., fig. 33. 



Frond large; constriction deep, linear ; segments in front - 

 view sub-t)'apezoidal, widely and roundly inflated at the base, 

 then tapering and slightly concave towards the ends, which 

 are wide and straight, the angles very slightly dilated. 

 Cytioderm punctate. On each segment are a number of 

 strong simple spines, neither dilated nor forked : most of these 

 are disposed in groups on the edges of the basal inflations in 

 front-view, others in pairs or in threes on the ends and at the 

 terminal angles, a few are scattered or in short rows on the 

 surface. Median inflation not to be made out in front-view ; 

 granules none. End-view elliptical, with a very slight median 

 inflation ; the spines arranged iii a longitudinal band, most 

 numerous towards the two ends, and with a parallel row of 

 only a few spines at each side of the band. 



Long., 89 jx; lat., 71"5 /x; crass., 35"a jx ; long, spin., 4-5 jx. 



Eutherford's Swamp, Otaki. 



The main distinction, it would seem, between the genera 

 Cosmarium and Xanthidium lies in the usually truncate and 

 granular projection which, in addition to the spines, occupies 



