BY G. I. TLAYFAIR. 475 



Var. PYGM^UM, n.var. (Pl.xii., f.6). 



Forma inflatione nulla vera, sed paiillo supra basin constric- 

 tione levi; apices versus leviter attenuata; apicibus truncatis 

 glabris; sutura prosiliente. Endochroma in taenias disposita. 

 Long. 206; lat. bas.l2; centr.l2j ap.9/x. 



Botany(108). 



COSMARIUM RECTANGULARE Grun. 



A large number of well-known "species" combine to form the 

 life-history of Cos. rectangulare. All of them are mere growing 

 forms, developing one into another under suitable conditions. 

 Tiiere is not the slightest doubt about these identifications, 

 as all the forms occur together, and show that peculiar likeness, 

 under the microscope, which it is impossible to describe or put 

 on paper. Wherever one is found, the others are sure to appear 

 on diligent search. The species is very local round Sydney; after 

 large and repeated gatherings, not a single one of any of the 

 forms here mentioned has been obtained from such rich localities 

 as Coogee, Botany, and Centennial Park. The species is entirely 

 confined to the clay-soil district of Auburn, Guildford, Fairfield, 

 Canley Vale, etc., where it occurs in profusion; and although 

 there are other and permanent waters in the vicinity, yet its 

 variations are not found except in the tiny drainage-pools and 

 swampy patches of ground along the Southern railway line, and 

 at Auburn. Nor have any of them been noted in the Sydney 

 water-supply, the drainage of a large area at some distance from 

 Sydney. As confirmatory of my conclusions about these forms, 

 it should be remarked that many years ago at Collector, 250 

 miles from Sydney and 2300 feet above sea-level, I found all the 

 principal variations associated together before. 



The "species" included in this life-history are Cos. pseudopi-o- 

 tuherans Wilie(not Kirchner), and /3 angustius Nord., Cos. sulca- 

 tum Nord., Cos. repaiidum Nord., Cos. sexangulare Lund., Cos. 

 hexagonum Elfv., Cos. Elfvingii Rac, and var. saxonicum Rac, 

 Cos. cydopevm Playf., Cos. odontopleurum Arch.(Koy »k Bissett,. 



