34 ON SOME NEW AND RARE DESMTDIE^. 



sunt, a, cellula a fronte ; h, a latere; c, a vertice ; d, oblique; 

 e, basi visa Jamaica iu Morces Gap ad Gordon Town. Leg. 

 J. Hart, 1884. 



2. EuASTRU.M vERRUcosuM Elu'enb. /3. simplex n. var. — Of stout 

 habit, terminal lobe very short and with very shallow incision ; 

 central inflation cither none or very small ; no other. It is nearest 

 to the Cosm. in Reinsche's Coutrib. xvi. 9 ; the verrucse are perhaps 

 somewhat larger than in the typical plant. Long. 85 fi, lat. 65 fi ; 

 width of apical lobe 33 /x, thickness 25 /a. 



3. CosMARiuM viRiDis Corda, Colopelta viridis Corda, in Alma- 

 nach de Carlsbad, 1835, p, 206, T. 11, f. 28; Cosmariiim Cordanum 

 (Breb.) Eabenh. Fl. Europ. Alg,, P. iii. page 177. — It approaches 

 nearly to a species figured by De Notaris among the forms of C. 

 palcmjula, fig. 34 c. G. Notaris de Elementi per lo studie delle 

 Desmidiace^e italiche ; also to the forms of C. f/Iohosum and P. 

 curtum in Wille, Novaja-Semlja, Taf. xh. f. 43 and 73. In the 

 absence of any definite knowledge of the size of Corda's plant I 

 think it best to class it as above. Pictou, Nova Scotia. Length 

 55 |M,, breadth 30-33 fi ; breadth of constriction 22 /u., 



4. Micrasterias ceratofera, n. sp. — Large, about one and a 

 half times longer than broad, deeply constricted at middle, leaving a 

 wide angle; semi-cells three-lobed, angles bifid, furnished with a 

 strong spine. Polar lobe much attenuated, and having the spines 

 rather longer. This distinct and remarkable species appears to 

 bear the nearest relation to Micrasterias arcuataJisiii. and M. ascen- 

 dens Nord., but at first sight I was in some doubt whether its true 

 position might not be with the Staurastra. Membrane smooth, 

 length (s. acul.) 27 /x, breadth (s. acul.) 55 /a, thickness 27 /x, 

 breadth of isthmus 20 /x, width of polar lobe (s. acul.) 30 /x. 

 Rangoon, British Burmah, October, 1883. 



5. Xanthidium antilopeum (Breb.) Kutz., new var. canadense — 

 Large cells much inflated, deeply constricted, truncate ; spines 

 stout ; cytioderm minutely punctate, possessing no j)rotuberance or 

 graniilation, resembling the var. Minneapulcnse AVolle, Desmid. 

 U. States, L. ii. f. 16, in the possession of a fifth pair of spines, 

 the extra pair in the centre of each semi-cell. Pictou, Nova 

 Scotia. Length 77 /ix, breadth (s. acul.) 63 /x (c. acul.), 83.90 /x, 

 breadth of isthmus 14 /x. 



6. Arthrodesmus gibberulus, n. sp. — Medium size, cells 

 elliptic with Strang convergent spines ; without spines about as 

 long as wide, membrane smooth, cells with large inflation at the 

 upper side, giving them in the end view an almost spherical 

 appearance. Rangoon, British Burmah, Length 36 /x, breadth 

 (s. acul.) 35 /x (c. acul.) 54 ^, thickness 25 fx, breadth of isthmus 

 13 /x. 



7. Staurastrum minusculuin nov. sp. — Very minute, smooth, 

 semi cells subcuneate with rounded ends, slightly convex ; angles 

 produced laterally into straight diverging arms, rather longer than 

 the diameter of cell, surmounted by four aculeate spines set at 

 right angles. Nearest to N. gracile Rail's, but diflering in its 

 smaller size and forked apices. Length of arm 12.13 /x, diameter 

 of cell 10 fj.. Rangoon, British Burmah. 



