BY G. I. PLAVFAIR. 109 



1. Synopsis of Australimi fypes. 



The various species and variations found locally are fully dis- 

 cussed in the body of the paper; hence it is not necessary for me 

 to do more here than add a brief summary. Representatives of 

 17 species have been observed, but, in two cases, 0. crai-sa Wittr., 

 and 0. nodulosa W. West, the types themselves have not been 

 noted. Tlie total number of local forms, therefoi'e, amounts to 

 15 specific types, 14 variations, and 3 forms — 32 in all. Of 

 these, 19 (including nom. nov.) are here described as new, viz., 

 6 species, 11 variations, and 2 forms. 



Species. — These new species are established principally on the 

 basis of the shape of the vegetative cell, or autospore, and, in 

 this, they are in line with all those published hitherto. 1 do 

 not, however, consider any of the species of Oocystis to be biologi- 

 cally distinct, but merely polymorphic forms of one organism. 

 It may be argued that the various types always retain their 

 specific characteristics. They do, and they do not. It is true that 

 any specified form gathered from many different localities in a 

 country, or even from many different parts of the world, always 

 exhibits the same shape, peculiai-ities, and range of dimensions. 

 But, on the other hand, the same form, when closely observed in 

 any given locality, will l>e found to be by no means as fixed and 

 unalterable as it seemed. It may be noted mixed with variations 

 of the same type, and even with forms of a different type, yet 

 obviously connected with it. A goofl illustration of this is found 

 in 0. apiculata West. This species in its size, shape, and apiculus 

 (found in no other type) possesses a group of characteristics which 

 make it very distinct. It has also what, as far as my observa- 

 tion goes, is not found in any other species, viz., a broad, mucous 

 lining to the membrane, such as may l)e observed on a larger 

 scale in forms of Eremosphcfiva. Specimens of the type are plenti- 

 ful in sample No. 88, but mixed with them are others moi-e slender 

 and more elliptic, and also another type without an apiculus, 

 and approximating in shape to 0. laciistris. Nevertheless, this 

 var. simplicior has the same nuicous lining characteristic of the 

 type, and its dimensions connect it with the smaller forms of the 



