Dr. G. J. Hinde — Western Australian Fossils. 203 



there is no doubt that the alleged ccenenchymal gemmation — the 

 special point brought forward by Waagen and Wentzel in favour of 

 the alliance of these forms to Corals — certainly does not take place 

 in H. dendroidea, and there is no satisfactory evidence that it occurs 

 in the Indian species of the genus described by these authors. 

 They further appeal to the figure given by Nicholson and Foord of 

 Fistulipora incrustans (Ann. and Mag. Nat. Hist. ser. 5, vol. xvi. 

 p. 501) as showing the same mode of increase by ccenenchymal 

 gemmation ; but it is evident that the figure referred to gives no 

 indication of the development of the cells or autopores from the 

 mesopores ; it merely shows that the former have been sectioned 

 obliquely. The real origin of the cells or autopores in this species 

 is by growth from the basal lamina, precisely in the same manner 

 as in Hexagonella dendroidea described above. 



This species was originally placed by Mr. Hudleston in the genus 

 Evactinopora, Meek and Worthen, but it has no close relationship to 

 E. radiata, the type of this genus. It appears to me very doubtful 

 whether the form named H. (Evactinopora) crucialis, Hudleston, is 

 really distinct from II. dendroidea, as the difference consists merely 

 in the mode of growth, a feature hardly of specific importance. 

 H. ramosa, W. & W., though similar in mode of growth to H. 

 dendroidea, has its cells only about half as large as in the latter 

 species, and is consequently distinct. 



Distribution. — Carboniferous, Gascoyne River. 



Genus Rhombopora, Meek. 

 Rhombopora tenuis, Hinde sp.n. PI. VIIIa. Figs. 4, 4a. 



Imbedded in some pieces of rock from the Gascoyne River are 

 several fragments of a small branching polyzoon, which in micro- 

 scopic characters are similar to the genus Rhombopora. The speci- 

 mens are cylindrical and branching, about P5 mm. in diameter ; the 

 cells spring from an imaginary central axis, and at first are nearly 

 vertical or slightly oblique ; they then curve somewhat abruptly and 

 open approximately at right angles to the surface of the branch 

 (Fig. 4a). In the axial portions the cells are subcircular in section, 

 with thin walls ; at the point where the outward curve commences, the 

 walls are considei'ably thickened. The cell-apertures are oval, about 

 •2 mm in width with definite fibrous margins ; in the interspaces 

 between them there are well-marked interstitial tubes and spines 

 (Fig. 4). I have not recognized any tabula? in the cells. 



From a comparison with specimens and sections of Rhombopora 

 interporosa, Phill. sp., kindly supplied me by my friend Mr. John 

 Young, F.G.S., I find a very close resemblance in microscopic struc- 

 ture to the Australian species ; at the same time there is also a certain 

 resemblance to such forms as Monticidipora ? tumida, Phill. sp., and 

 more particularly to a slender variety of this species from the 

 Carboniferous strata of Northumberland, which has been named var. 

 miliaria by Prof. Nicholson (Genus Montiadipora, p. 123, pi. iii. 

 figs. 2, 2c). 



Distribution. — Carbonifei'ous, Gascoyne River. The specimens are 

 associated in the same matrix with Ilexagouella dendroidea. 



