204 



coarsly wrinkled and striate, slightly inabricately laminate, crenu- 

 lating the lateral angles. Exothecal outgrowths not observed. 



Obs. — The principal characters of A', iiiterpuiiclalimi are its 

 remarkable Ca/ceo^rt-like outline, prominent counter septum, and 

 highly and coarsely vesicular structure. The relation in which 

 R. inter punctatujii stands with regard to R. auatrale has already 

 been commented on, but the form, and moi'e highly developed 

 septa will tend to separate the species. 



In outline R. inteiyunctatuni apj^roaches nearest to Rhizo- 

 phyllum gotlandicum, F. Roemer, * and R. tennesseeube, F. 

 Roemer,t but it is a smaller species, and the longitudinal curve 

 of the corallum is proportionately greater in relation to its size. 



Tlie septa in R. interpuiictatum, unlike those of Goniophyllmii 

 pyramidale, are completely hidden by the highly developed 

 vesicular tissue, instead of passing over the latter and disappear- 

 ing at the bottom of the calice. Mr. Mitchell's specimens are in 

 the form of internal casts of the calice, with the vesicular tissue 

 removed, precisely in the same condition as De Koninck's were. 

 The septa on the ventral side are vertical and increase in length 

 from the lateral angles towards the counter septum. They are 

 very finely granulated, and when in the least degree worn, with 

 their angular inner sides rubbed off, appear double. No doubt 

 Lindstrom's suggestion that each is composed of two lamina:? 

 satisfactorily accounts for this. In counting the septa this 

 feature must be taken careful note of, otherwise the total number 

 will be accepted as exactly double. At the lateral angles and on 

 the dorsal side of tlie calice the septa are represented by minutely 

 granulated, very tine ridges, the granules in a single row, conform- 

 ing in the curvature to the outline of the corallum. 



LocalifAj and Horizon. — Hatton's Corner, near Yass (J. A. 

 Wall), Silverdale ( J. Mitchell); Upper Silurian, probably Wenlock. 



Collections. — Australian Museum, J. A. Wall, and J. Mitchell. 



General Remarks. — Both Rldzophyllum australe and R. inter- 

 punctatum agree with the genus RhirMphyllum, rather than 

 Calceola, in the highly and openly vesicular nature of tlie corallum. 

 On the other hand, the total apparent absence of exothecal 

 structures in the form of anchoring stolons from the flattened 

 under surface show a departure towards the last named genus, in 

 which there is no trace of tliem. The arrangement of the vesi- 

 cular tissue of the corallum is precisely similar in both our species 

 to that seen in Goniophyllum—ininndihuViionn layers, with the 

 convexities of the vesicles directed upwards and inwards. This 

 structure is particularly well shown in one of Mr. Wall's speci- 

 mens of R. inter p'unctatum (PI. xxx., Fig. 7), from which the 

 epitheca has been removed by weathering. It is also apparent 



* Lindstrom, Bihang K. Vet. Akad. Handl. Stuckholia, 1882, vii. No. 

 •i, t. 3, f. i. 

 t Sil. Fauua Westl. Tennessee, 1860, p. 77, t. 5, f. 1. 



