234 C. M. Mapledone: 



Locality, Mitchell River (J. Dennant). 



A veiy slender delicate species, with remarkably small zooecia. 



Idmonea parvula, n. sp. (PI. VII., Fig. 4). 

 Zoarium 2.2 mm. long, 0.8 wide, with a narrow .selvedge. Zooecia 

 in two series of three, immersed. Thyrostomes exserted, 0.3 mm. 

 high; distance between series, 0.2 to 0.3 mm. 



Locality, Mitchell River (J. Dennant). 



A single specimen. The figure shows the entire zoarium, and 

 is drawn so as to show the regular disposition of the zooecia on 

 one side, and a lateral view of the exserted thyrostomes of the 

 zooecia on the other side of the zoarium. 



Idmonea concinna, n. sp. (PI. VII., Fig. 5). 

 Zoarium short, 2 mm. long, 1.2 mm. wide, with a selvedge. 

 Zoo'ccia in two series of four to six ; distance between the series 

 0.2 to 0.3 mm. Thji'ostomes connate, exserted about 0.2 mm. 



Locality, Filter Quarries (T. S. Hall). 



This is a very short, cmmpact form. The figure shows the 

 complete zoarium and is drawn so as to show the regular series 

 of connate thyrostomes on one side, and the edge shows the 

 lateral view of the other series. 



Idmonea angustata, u. sp. (PI. VII., Fig. 6). 

 Zoarium narrow, branched. Zooecia 0.05 mm. wide, in two 

 series of foiir to five. Thyrostomes much exserted, distance 

 between each series 0.3 to 0.45 mm. Ooecium tumid, overlying 

 the zooecia, sitvuited below a bifurcation. 



Locality, Filter Quarries (T. S. Hall). 



This is a very distinct form, the zooecia are very narrow and 

 veiy regularly disposed. 



Idmonea unlseriata, n. sp. (PI. VIT., Fig. 7). 



Zoarium bra,nching. Zooecia large, in single series, 0.2 mm. 

 wide, 1.5 mm. long. Thyrostomes 0.5 to 1 nmi. apart. 



Locality, Mitchell Rivei' (J. Dennant). 



This species is peculiar in that there is only a single series of 

 zooecia. It may posisibly be separated generically from LlDionea, 

 but the character of its growth seems to be Idmonean, though 

 the series of zooecia are single. 



