BV G. I. PLAYFAIR. 5 



variations, therefore, may be relied upon to be of some fixity of 

 character. The Lismore forms are rarer, more interesting and 

 distinct than those from Sydney, e.g., Tr, bulla var. australis^ Tr. 

 conica vars., IV. Lisinorensis, Tr. verrucosa Stokes, Tr. scabra 

 and vars., Tr. eurystoma Stein, and vars., Tr. caudata var. aus- 

 tralica, Tr. urceolata var. Girardiana. On the other hand, the 

 tailed forms were almost confined to Parramatta Park, and Duck 

 Creek, Auburn. 



Nomenclature.— With regard to the nomenclature, of those 

 mentioned, 25 are ranked as species, 75 as variations, and 4 as 

 forms. The species, of course, are the conventional species 

 current in microscopical studies for purposes of classification. I 

 use the terms "species," "variation," and "form" as merely 

 three degrees of comparison in distinctness of outward configura- 

 tion — in Trachelomonas, the shape of the lorica. In the forms 

 and variations there is generally some biological connection with 

 the type, though not always, e.g., Tr. clavata var. spinosa, Tr. 

 urceolata var. Girardiana, and Tr. caudata var. australica; these 

 are each variations of a type-Joj-m, but probably are not developed 

 from the type itself. They are neither found in company with 

 it nor replacing it, but are collateral Australian types. The 

 conventional species, on the other hand, are merely type-forms, 

 and are not indicative of any biological distinctness. They do 

 not generally, indeed, develop one into another, but each comes 

 into existence by development from the root-form of the true 

 species. I recognise only two biological species in Trdchelomonas 

 — (1) comprising all the rounded forms, (2) the tailed (stipitate) 

 forms, and of these two even, the latter is of doubtful distinct- 

 ness (c/! Stein, T.xxii., f.22, where 7V. hispida is portrayed with 

 a tail; also Tr. subglohosa mihi, PI. v., f,20, 21, which simulates 

 Tr. volvocina, and of which one form is obscurely tailed), Among 

 the rounded varieties, Tr. volvocina is the root-form, and in the 

 stipitate, some minute form like Tr. sessHis var. minima, the 

 conventional species l^eing merely polymorphic forms of growth 

 developed from them. I have come to realise, however, that any 

 system of nomenclature based on polymorphism is futile. Some 

 attempt of this kind was made by me in " Polymorphism and 



