BY G. I. PLAYFAIR. 105 



Var. PORRECTUM (Nord.). (PL iii., f.l9, 20). 

 Long. max. 68-72, centr. 64-70, lat. 70-74, has. 54-60, isth. 20, 

 crass. 30 /x. 



Lismore(12). Cf. Nord,, Desm. C. Braz., T.3,f.28. 



MiXKD FORM. (PI. iii., f.21). 



a. Var. porrectum (Nord.). 



Long, semic. 36, lat 74, isth. 18, bas. 56 fx. 



b. Var. quadrum (Lund). 



Long, semic. 36, lat. 64, bas. 56, crass. 36 /x. 



Lismore(17). 



The above are, undoubtedly, all forms of one species Those 

 in samples 17, 18, were gathered from the same place on the same 

 day; those in 12, from the same position two months earlier. 

 They all have the same characteristic end-view, oblong almost 

 cylindrical, with paiallel sides and broadly rounded ends. The 

 arrangement of the granules is the same also, viz., in vertical and 

 decussating series. It should be noted that the forms of Cos. 

 porrectum, in figs. 20 and 2 la, are really intermediate between 

 Cos. porrectum Nord., type, and Cos. suhlatum Nord. The forms 

 of Cos. dentiferum may nearly always be recognised by the large, 

 quadrate, smooth space at the isthmus, caused by the tendency 

 in the semicells to be reniform, above and below which are 

 generally five granules forming an angle. Besides those men- 

 tioned here, other desmids included in this species are :— Cos. 

 reniforme Ralfs, and P covipressum Nord., the latter widespread 

 in this country, Cos. orthopleurum, R.&B., Cos. Tnargaritatum 

 (Lund), Cos. pardalis Cohn, Cos. lacanatum G. S. AVest, and 

 Cos. pseudohroomei Wolle. 



PROTOCOCCOIDE^. 

 Genus Chlamydomonas Ehr. 

 Chlamydomonas intermedia Chodat. 

 Long. 17, lat. 10 /x. 

 Lismore(13). 



Four in a mucous ccenobium, stirring but not yet motile, the 

 contractile vesicle, however, could be seen working Chodat 



