200 Br. G. J. Hinde — Western Australian Fossils. 



referred by De Koninck to P. fastuosus (Q.J.G.S. vol. xix. 1863, p. 5, 

 pi. i. fig. 4); but it differs in the narrower fenestrules ; the dissepi- 

 ments are also larger and carry cells. Only a single fragmentary 

 specimen known. 



Distribution. — Carboniferous, Gascoyne Eiver. 



Genus Hexagonella, Waagen and Wentzel. 



Hexagonella dendroidea, Hudleston, sp. Plate VIII. Fig. 6 and 

 VIII a. Figs. 5-5 d. 



1883. Evactinopora dendroidea, Hudleston, Quart. Journ. Geol. Soc. vol. xxxix. 



p. 594, pi. 23, figs. Za—Zd. 

 1886. Hexagonella dendroidea, "Waagen and "Wentzel, Mem. Geol. Surv. India, 



ser. xiii. p. 913. 

 1889. Evactinopora dendroidea, E. Etheridge, jun., Proc. Linn. Soc. New South 



Wales, toI. iv. p. 207. 



The examples of this species appear to be more abundant than 

 those of any other fossil from the Carboniferous Limestone strata of 

 the Gascoyne Eiver, and the numerous specimens in the collection 

 afford an excellent opportunity of ascertaining its minute characters. 

 Since this form was described by Mr. Hudleston in 1883, several other 

 species of the same genus have been recorded by Waagen and Wentzel 

 from the Carboniferous strata of the Punjab, and these authors have 

 proposed the new genus Hexagonella for their reception. As will be 

 shown later on, the characters of this genus are so similar to those 

 of Fistulipora, M'Coy, that it may be doubted whether it should be 

 considered as more than a subgenus ; but at the same time the 

 species included in it possess in common some slight structural 

 features, which make it desirable to place them in a distinct group, 

 and I propose therefore to retain Waagen and Wentzel's name. 

 Considerable interest attaches to this genus, since, according to these 

 authors, it exhibits a mode of increase by so-called coenenchymal 

 gemmation, which, in their view, indicates distinctly that this and 

 similar allied forms should be considered as Corals rather than 

 Polyzoa. This evidence in favour of the coelenterate nature of these 

 organisms has been quoted by Prof. Nicholson, 1 and by the late 

 Prof. Neumayr, 2 as strong proof of the correctness of the view that 

 they are Corals. As the result of a careful study of numerous 

 sections of the Australian species, which there can be no doubt is 

 closely similar to the Punjab forms, I can find no indication of this 

 alleged coenenchymal gemmation, but, on the contrary, a mode of 

 growth from a basal lamina which is strongly characteristic of 

 Polyzoa, and as in other structural features these forms resemble 

 Polyzoa. I accept this view of their character, which, it may be 

 said is that originally held by Mr. Hudleston. 



Hexagonella dendroidea occurs as solid, straight or curved stems 

 or branches, ranging from 30 to 80 mm. in length, from 10 to 

 22 mm. in width, and from 5 to 15 mm. in thickness. The specimens 

 are all fragmentary, the stems are usually compressed, sometimes 

 nearly cylindrical, of an even width and thickness, except where 



1 Manual of Palaeontology, third edition, vol. i. p. 352. 



2 Die Stamme des Thierreichs, p. 324. 



