BY G. I. PLAYFAIR. 181 



repentead apices convergentibus; apicibus latis truncatis; arigulis 

 basalibus medianis apicalibusque dentibus singulis munitis. In 

 centro semicellulae tumore glabro, rotundato. A vertice semi- 

 cellulae oblongae, crassae, regulariter hexagonae; apicibus latis 

 truncatis, angulis in dentes minutos singulos productis; utrinque 

 in medio tumore rotundato instructae. Membrana punctata 

 paullo incrassata. 



Long. 54; lat. 45; crass. 33fi. 



Rose's Lagoon, Collector. 



Most like X. Chahibinskii Eich. & Rac, Nowe Gatt. Ziel T.3, 

 f.28. 



Compare JT. fasciculatiun var. perornatuin Nord., Alg. N. Z. 

 T.4, f.23, with which the above coincides in size and somewhat 

 resembles in outline. It differs, however, in the end view most 

 of all, which in X. hexagonurti is very broad and regularly hex- 

 agonal with dentate angles. The tumour is different also, and 

 the spines wanting. Tiie one cell seen was probably mature, 

 since the membrane was incrassate. Cf. also X. trilobum Nord., 

 in C. Braz. T.3, £35, and X. suhtrilohum West, in Journ. Bot. 

 XXXV., T.368, f.l4. 



Xan. decemdenticulatum, n.sp. (T.iii. f.l2). 



Xan. mediocre, subcirculare, paullo longius quam latum, medio 

 sinu cuneato profunde constrictum. Semicellulae subreniformes, 

 angulis inferioribus rotundatis, lateribus convexis apices versus 

 levissime retusis, apicibus angustis truncatis; semicellulae utroque 

 latere denticulis geminatis 5 munitae, denticulis adscendentibus 

 paullo curvatis in centro tumore verrucoso ornatae; a latere visae 

 circulares; a vertice ellipticae, apicibus rotundatis, utrinque 

 tumore praeditae. Membrana punctata. 



Long. 81; lat. 76; crass. 40, long. dent. circ. 3yL. 



Ewenmar, Trangie. 



Very similar to X. fasciculaturn ^ ornatum Nord., in Desm. 

 Greenland, f.lO, but larger, and the six pairs of subulate spines 

 or straight aculei in the semicell are replaced in this form by ten 

 pairs of small very sharp-pointed teeth, which, with the exception 



