154 Rev. T. Hincks's Contributions towards 



each side ; aperture flattened above, narrowing downward, 

 rounded at the lower extremity (very much in the form of a 

 heraldic shield), surrounded by a slightly thickened rim ; at 

 the top of the cell four spines, placed two on each side, the 

 foremost pair stout, suberect, and branched, like a stag's horn, 

 the upper tall, slender, and slightly forked ; between them a 

 raised avicularium with pointed mandible, placed transversely 

 on the margin of the cell, or projecting straight outwards 

 from the back ; frequently a large raised avicularium at the 

 bottom of the cell. Ocecium very shallow, galeriform, smooth, 

 the oral surface much sloped, so as to expose the opening ; a 

 raised line arching across the front a short distance above the 

 opening, inclosing a narrow subhyaline belt ; an avicularium 

 on the summit, placed transversely ; two spines in front of the 

 ovicell, and two at the sides (Plate VIII. fig. 1), Zoarium 

 white or brownish, or of a rather deep purplish colour, 



Var. a. Ooecium much deeper (less shallow), almost sub- 

 quadrate, the oral surface not sloped ; a raised rib in front 

 inclosing a subtriangular space ; one or two avicularia at the 

 back (PI. X. fig. 3). 



Log. Victoria {MacGilUvray) ; var. a, off Curtis Island, 

 Bass's Straits {CajU. Cawne Warren). 



I have thought it desirable to give a detailed description of 

 this species, as MacGillivray has contented himself with a 

 very brief diagnosis. Busk's account of his M. cervicornis is 

 almost equally brief; and between the two there is some 

 difficulty in deciding with any certainty as to the identity or 

 otherwise of the two forms. 



The differences in the ooecium are striking and curious ; 

 but they can only be regarded as varietal. The spines are 

 articulated to a fixed tubular base, and are easily detached ; 

 in their absence it is somewhat difficult at first sight to recog- 

 nize the species. 



Note on Membranipora transversa^ Hincks. 



When I described this form (' Annals,' July 1880) I was 

 not aware that Mr. Hutton had been before me. I had not 

 then seen his paper in the ' Proceedings of the Royal Society 

 of Tasmania' for 1877 (pubhshed in 1878), in which he has 

 characterized it as M. cincta. Of course the name transversa 

 must be cancelled ; and I can only hope that it may drop out 

 of sight and give no further trouble. 



In a paper presented to the Royal Society of Victoria early 

 in 1880 Mr. MacGillivray has given a fuller account of the 

 same species, and proposes to refer it to a new genus, which 

 he names Diplopora^ and of which the distinctive characters 



