A MONOGRAPH OF THE TERTIARY POLTZOA OP VICTORIA. 61 



This family group lias already been suggested by Hincks (A.M.N.H., December, 

 1891) in a valuable criticism on Cribrilina monoceros and Siantopora ferox, in 

 which he points out the relationship of these two species and the real developmental 

 structure of the perforated front wall. Jullien (Cap Horn Bryozoaires, p. 62) 

 places C. monoceros under a distinct genus — Arachnopusia — of which he makes a 

 separate family. The characters on which he founds both family and genus are, as 

 Hincks remarks, only of secondary importance, and at the most of merely specific 

 value. 



H. monoceros differs from K. ferox in having the zooecia in their early 

 membraniporidan state closely united and not disjunct and joined by communi- 

 cating tubes as in the last named species and probably in H. halli. This junction 

 of the early zooecia by membranous tubes is similar to the arrangement in many 

 species of Beania (Diachoris) and several species of membranipora, and the attach- 

 ment by posterior radical tabes shews a farther alliance to M. raclicifera. 



Hiantopora, McG. 

 Characters as for the family. 



1. R. halli, n.sp. PL VIII., fig. 25. 



Zooecia indistinct, alternate, very deep ; front wall covered by a calcareous plate 

 with large elliptical or ovate perforations, the anterior edge being entire, sharply 

 turned forwards, and surmounted by a pair of slight eminences with small depres- 

 sions (seemingly avicularian) on their summits ; the base of the zooecium behind 

 the perforated plate, smooth, with a transverse reniform pore, from which descends 

 a short, sharp ridge ; a large raised avicularium, Avith long mandible, extending 

 outwards from each side opposite the reniform pore to the elevation of the retiform 

 plate of the contiguous zooecium ; anterior part of the zooecium much depressed ; 

 thyrostome having a minute avicularium above its straight upper edge, and a stout 

 rigid calcareous spine on each side. Ooecium mitrif orm, immersed. Dorsally the 

 inferior portion of the zooecium much projecting, with numerous small conical 

 elevations, ending in calcareous radical tubes. 



M.C. 



Unfortunately the only specimen I have seen does not show the zoeecial growth 

 satisfactorily, the marginal zooecia being well calcified. So far as I can make out, 

 the inferior reniform pore is formed by the junction of a small plate from each 

 margin ; from the upper of these plates two or three processes grow forwards and 

 anastomose to form the perforated front wall ; the elevated anterior bar seems to be 

 constituted by a growth from the bases of the avicularia of the contiguous zooecia. 



