16 , Mr. R. Kirkpatrick on 



series, from five to nine in each series ; zooecia slightly pro- 

 jecting, surface obscurely granular in old cells, punctured in 

 young cells ; section of branches showing a transverse thin 

 double lamina, which projects beyond the ends of the branches. 

 Ooecia oval, '8 millim. long by '6 broad, with four to six 

 zooecial openings on surface. 



The genus Bidiastopora was founded by d'Orbigny for the 

 reception of forms with compressed branches, the cells on 

 each side having a quincuncial arrangement, and with a 

 lamina in the middle of the branches. The main difference 

 between Entalopliora (Lamouroux) and Bidiastopora lay in 

 the fact that in the former the branches are compressed, in 

 the latter rounded. In some parts of the zoarium the lamina 

 may be obscure or even absent ; but its occurrence in any 

 part would indicate that the species should not be classed in 

 the genus Entalopliora. 



In arranging the Cyclostomata systematically great im- 

 portance is necessarily attached to the structure of the zoarium, 

 since the individual zooecia present such slight differences. 

 The presence of the median double lamina is a sufficiently im- 

 portant structural characteristic to warrant the reintroduction 

 of d'Orbigny 's genus. In Entalopliora {Pustidop>ora) the 

 rounded branches are formed of fascicles of zooecia, and a 

 transverse section is porous throughout. 



Family HeteroporidaB ? 



Genus Heteeopora, Blainville. 



lleleropora moiandrina^ n. sp. (PI. II. figs. 8, 8 a, 8 J, 8 c.) 



Zoarium forming a thick crust, loosely encircling stems of 

 Amathia; the surface marked with irregularly arranged ridges 

 and depressions ; the crests of ridges smooth and generally 

 bare of zooecial pores ; zooecial orifices circular, with thick- 

 ened tuberculated border ; zooecia surrounded by five or six 

 cancelli. 



The specimen above described differs considerably from 

 d'Orbigny's Pletliopora cervicornis (' Paleontologie Fran^aise,' 

 torn. V. p. 1045, pi. 799. figs. 4, 5), but resembles a specimen 

 described and figured as Heteropora cervicornis, d'Orb., by 

 Mr. Waters (Journ. Roy. Micr. Soc. vol. ii. p. 390, pi. xv.). 

 MacGillivray's Densipora corrugata (J. R. S. V. 1880) 

 appears to resemble very closely Htteropora cervicornis, d'Orb. 

 The specimen from Port Phillip measures 10x7 millim. 



A fully developed specimen of H. mceandrina would per- 



