A MONOGRAPH OP THE TERTIARY POLYZOA OP VICTORIA. 51 



small avicularia supported on papilliform elevations. Ooecium above the aperture, 

 semicircular, depressed, with a thickened rim. 



M.C. ; W.P. (W.). Living. Australia and Florida. 



Caleschara, McG. 



Zoarium encrusting, or erect and nni- or bilaniinate. Zooacia separated by 

 distinct raised calcareous margins ; front covered by a thick epitheca, beneath 

 which the calcareous front wall is bevelled to the depressed centre ; on each side of 

 the calcareous front is a longitudinal fissure, and across the upper part a thickened 

 bar, leaving a membranous portion above containing the thyrostome, the operculum 

 of which is incomplete. Ocecia altered and expanded zocecia. 



1. C. denticulata, McG. PL VI., figs. 8, 9. 



C. denticulata, McGr. in P.Z.V. 48 ; Busk, O.P., Pt. I., p. 77 ; Membranipora 

 denticulata, Hincks, A.M.N.H., February, 1881. 



Characters those of the genus. Lamina granular ; lateral fissures denticulate ; 

 aperture occupying rather less than one-fourth of the area. 



S.P. ; M.C. ; C.B.; W.P. A common living Australian species. 



In the fossils of course only the deeper calcareous front wall is seen. The 

 calcareous part between the fissures and the thickened cross-bar are usually worn 

 away, when the Zooecia have a very different appearance, seeming to have a large 

 nearly elliptical aperture. In some specimens, however, these parts are well 

 preserved, and perfect and worn zooecia may be seen in the same fragment. 



Of the systematic position of this curious form, opinions may, as Mr. Busk 

 remarks, well be divided. Young recent zooecia have the structure of Membranipora, 

 but with age the deeper calcareous wall with its lateral fissures and cross-bar becomes 

 developed ; Hincks at first included it in the genus Membranipora, but subsequently 

 (A.M.N.H., July, 1887) adopts the genus Caleschara and places it in the Stegano- 

 porellidse. On the whole I consider its affinities are more with the Menibraniporidse 

 in which I include the genus, although I am by no means satisfied that Hincks' 

 view may not be the correct one. 



Family Steganoporellidje. 



Zoarium expanded and crustaceous, or free and uni- or bilaminate, or erect and 

 cylindrical. Zooecia separated by thick calcareous margins, divided into two 

 chambers, an upper closed by a thick epitheca which carries the operculum, and a 



H2 



