BY G. I. PLAYFAIR, 103 



Shows its intimate connection with Cos. Blyttii in the char- 

 acteristic absence of the tumour. 



Cos. Blyttii var. RiCHMONDiiE, n.var. (PI. iii., f. 12). 



Forma var. Novce-Sylvice proxima, paullo autem major, apicibus 

 angustioribus. Semicellulse lateribus e basi divergentibus, anguHs 

 basalibus baud rectis. Apicibus 4-granulatis; lateribus crenis 

 bigranulatis 2, crenis simplicibus basalibus 2; supra isthmum 

 tumore nullo nee granulis. 



Long. 24, lat. 20, ap. 7, bas. 16, isth. 6 ix. 



Casino (14). Cum priori. 



This form is intermediate between Cos. Blyttii and Cos. sub- 

 costatum f. minor. It follows the Australian form of the type 

 in having no papilla or granules above the isthmus. There is an 

 odd granule below the depression on either side of the apex. 



Var. Casinoense, n.var. (PI. iii., f.l3). 



In ambitu formse typicse similis, sed major. Semicellulse lateri- 

 bus crenis bigranulatis singulis, crenis simplicibus basalibus 2; 

 supra isthmum tumore plus minus circulari, 8+1 granulis serie- 

 bus verticalibus 3 ordinatis, ornatse. A vertice ellipticae, polls 

 late rotundatis, medio utrinque tumore 3-granulato instructse. 



Long. 24-26, lat. 20-22, ap. 10, isth. 6 /a. 



Casino (14). Cum prioribus duobus. 



Combines the form and marginal granulation of Cos. Blyttii 

 with the tumour of Cos. subprotumidiim. 



Cos. Seeleyanum var. elegans, n.var. (PL iii., f. 14-1 6). 



Semicellulse tumoribus granulis 9 in seriebus verticalibus 3 

 ordinatis; lobulis subapicalibus a tumore radiantibus. A vertice 

 ellipticae, utroque latere, in medio, tumore 3-granulato (lat. 5 /x) 

 ornatae, utrinque ad tumorem excavatse. 



Long. 24-26, lat. 20-22, ap. 12-13, isth. 6, crass. 13-14 /x. 



Casino (14). Cum prioribus tribus. 



Since Wolle described it from New York, this rare desmid has 

 only once before been reported, by Mobius from Victoria Park, 

 Brisbane. The apex is 4-granulate, but the two inner granules 

 show a tendency to become geminate. These four were all found 



