70 Proceedings of the Royal Society of Victoria. 



The dorsal surfaces of the ooecia only are visible, the front has 

 broken away. The species is very variable, in some specimens 

 the surface of the zooecia is simply somewhat irregular, in others 

 covered with large mamillae completely obscuring the shape of 

 the zooecia, and leaving the thyrostomes and dorsal surface of the 

 ooecia much depressed. 



Schizopopella chlithridiata, n. sp. (PI. VIII., Fig. 13). 



Zooecia oval, distal extremity ov^erlapping ; surface faintly 

 ribbed horizontally, tlie centre portion below the thyrostome 

 raised into a long smooth process ; on the rest of the surface are 

 a few small scattered pores or minute papillae. Thyrostome 

 arched above, broad curved sinus in lower lip. Avicularia 

 vicarious, with well-defined pores in more or less regular rows ; 

 mandibular cavity chlithridiate. Ooecia subglobose, immersed, 

 with a longitudinal umbo. 



Locality. — CYiiton Bank, Muddy Creek (T. S. Hall). 



A colony on a small bivalve shell. The great peculiarity of 

 this species is the vicarious avicularium and its chlithridiate 

 mandibular cavity. The ooecia are generally more produced 

 distally into a prominent umbo than the one figured, but the 

 portion illustrated was chosen as it shows three of the avicularia. 



Schizopopella ambigua, n. sp. (PI. YIIL, Fig. 14). 



Zooecia large, hexagonal ; margins raised ; surface covered 

 with large perforations. Thyrostome arched above; lower margin 

 with a very wide shallow sinus. Ooecia large, globose, slightly 

 immersed, perforated ; with a large acute avicularium, on the 

 distal part on one side, with the mandible pointing proximally. 



Locality. — Mitchell River (J. Dennant). 



This is a very striking species, as it has avicularia on the 

 ooecia. On one zooecium there is on one side of the thyrostome 

 a hemispherical avicularium, with a semicircular mandibular 

 opening. The thyrostome has a very wide shallow sinus, and on 

 this account I think this species should, with others having 

 similar thyrostomes, be relegated to a new genus, as they differ 

 so much from the typical forms with a narrow sinus. 



