638 RHIZOPODS OF SYDNEY AXD LISMORE, 



tangential view and seem to be, therefore, excavations or gran- 

 ules on the inner side of the test, or else chitinous deposits 

 actually within the substance of the test itself. Curious colours 

 are sometimes met with in this form; a dull green is not uncom- 

 mon, and I have met with a specimen rose-pink. 



ARCELr-A CRENATA, n.sp. (PI. xxxiv., f.4, 5). 



Test in side-view with a high, arched dome, sometimes very 

 much inflated, and as broad as the base, the margin showing 

 sometimes smooth, but generally crenate. The surface dented- 

 in, all over the dome, with small, equal-sized pits. Base some- 

 times with a rolled edge in side view. Many forms of this type 

 are found, but the pitted test and high, arched dome are char- 

 acteristic. 



Diara. 50-84, alt. 31-53; orif. 15-20, alt. 8-11//. 



I<^ very where, common. 



Arcella HEMISPH.EKICA Perty. (PI. xxxiv., f.6). 



Cf. Penard, Faune Rhiz., p. 400. Cash, Br. Frw. Phiz., i., 

 p. 1*20, makes this a synonym of A. vulgaris, but the shape is 

 quite distinct. Many varieties may be noted, but a more or less 

 hemispherical dome, with sides running evenly down at nearly 

 right angles to the base, is characteristic. 



Diam. 38-68, alt. 23-37; orif. 10-20, alt. 8-9/x. 



Everywhere, common. 



Yar. DEPHESSA, n.var. (PI. xxxiv., f.7). 

 Test with the dome in side-view somewhat depressed above. 

 Diam. 34-57, alt. 21-36; orif. 10-15, alt. 4-8/x. 

 Jiotany (152); Wyrallah (310); Lismore. 



Arcella discoides v. scutelliformis, n.var. 



Test much smaller than the type, with somewhat higher dome, 

 and much more rounded, basal angles. The orifice projects 

 about half-way into the interior, and is relatively very wide. 



Diam. 44-95, alt. 15-25; orif. 14-34, alt. l-Wfx. 



Auburn (139, 169); Wyrallah (310); Lismore (337). 



The type, as given by Penard and by Cash, is extremely rare 

 here. I have seen but a single specimen. (PL xxxiv., f.8). 



I 



