128 A MONOGRAPH OP THE TERTIARY POLYZOA OP VICTORIA. 



spaces for the openings of the zooecia ; thyrostomes little prominent or immersed, 

 the peristome below raised and entire or sinuated, and with a prominent rounded or 

 subcorneal eminence immediately below the lower margin. Posterior surface 

 strongly longitudinally fibrillate, the fibrillse minutely tubercular or granular and 

 the intervening sulci destitute of pores. 



B. 



8. R. involnta, n.sp. PI. XIX., fig. 3. 



Zoarium stout, branches irregularly dichotomously divided, slightly convex in 

 front, flat and depressed behind. Anterior surface with strong, sharply-raised 

 longitudinal ridges, between which are the depressions for the zooecia, the 

 depressions having a few pores ; the zooecia in the centre irregularly arranged, on 

 the margins arranged at regular intervals in transverse rows of one or two, the 

 external much projecting ; peristome in the central zooecia projecting and frequently 

 slightly prominent on each side and deficient above ; external zooecia with outer 

 margin of peristome much produced and pointed. Posterior surface flat or slightly 

 depressed, with longitudinal ridges, the broad intervening spaces usually crossed at 

 short intervals by transverse elevations leaving small pits with frequently a pore at 

 the bottom ; margin of branches regularly sinuated by the projection of the lateral 

 zooecia, with a thickened rim running upwards and downwards from the zooecia, 

 usually turned back to form an involuted rim, but occasionally above a zocecium 

 sending a branch to form one of the dorsal ridges 



C.B. 



A very peculiar and well-marked species. 



9. H. tenuis, n.sp. PI. XIX., fig. 4. 



Branches very slender, usually in three series of zocecia in the front. Anterior 

 surface smooth, divided into three series of depressions or furrows by raised smooth 

 margins, the depressions being wider at the orifices of the zocecia ; zooecia with the 

 thyrostomes directed forwards, circular, entire or sinuated at the proximal edge. 

 Posterior surface with wide, flat sulci, with a few raised pores separated by raised 

 crenulated margins. 



Belmont. 



10. H. diffusa, n.sp. PI. XIX., fig. 5. 



Branches long, slender, irregularly divided. Anterior surface with very obscure 

 ridges, granular or transversely tuberculated, numerous pores usually arranged 

 longitudinally, but except towards the extremities of the branches the zocecial 



