Vol. 62.] IX THE CARBONIFEROUS ROCKS AT RUSH. 317 



(3) The type-specimen figured by Micbelin r was derived from Tournai, 

 and therefore, presumably, from the Lower Avonian; all our 

 specimens came from the top of the Upper Avonian. 2 



1 

 Cyathaxonia contorta, sp. nov. (PI. XXIX, figs. 4 & 4 a.) 



Form : short, conical, cornute. 



Epitheca: strongly annulated and indistinctly costate. 



Calyx : boundary a circle, perpendicular to the axis ; rim sharp ; 

 inner slope radiated by a single series of equal, well-spaced septa : 

 from the middle of the floor projects the very prominent, tall, 

 laterally-compressed columella, the sides of which are roughened by 

 vertical ridges. 



Horizontal section. — Septa 30 to 40 in number, thick, 

 simple, and bent. A distinct septal break is occupied by a short 

 septum. All the septa are attached to the thick wall by an en- 

 larged base. 



The central area has an irregular, heart-shaped boundary, which 

 is strongly thickened ; within this bounding ring is the cross- 

 section of the columella, finely serrated on its sides, the interspace 

 being occupied by vesicles. 



The interseptal spaces show a very few tabular intersections, the 

 tabulae having a very high slope. 



Occurrence. — In the Cyathaxonia-Be&s, where it is less 

 abundant than the associated C. rusliiana. 



Relationship. — C. contorta resembles 0. rushiana only in its 

 central area. The septa differ markedly : in C. contorta they are 

 single, bent, and numerous ; in C. rushiana they are few in 

 number, paired, and straight. In O. contorta the interseptal spaces 

 are traversed by sparse tabulae ; in C. rusliiana there are appa- 

 rently neither tabulae nor vesicles. The form of C. contorta is a 



1 ' Icon. Zooph.' 1840-47, p. 258 & pi. lix, fig. 9. 



2 M'Coy, however, states {loc. cit.) that he compared Cyathaxonia comu, 

 M'Coy, with specimens from Tournai, and found the ' coincidence exact.' 



Mr. A. L. Leach, who has collected very carefully from the Carboniferous 

 Limestone of the Tenby district, has very kindly allowed me to examine two 

 specimens of a Cyathaxonia which he has discovered in the Lower Avonian of 

 that locality. 



In both specimens the calyx is well exposed, and exhibits a prominent 

 columella which is apparently solid. 



The septa, as seen in the calyx, are simple and alternate. The larger septa 

 extend to the columella, the shorter project a very short distance from the wall. 

 (It is unfortunate that the friable nature of the specimens forbids any attempt 

 to obtain a horizontal section.) In the smaller specimen there are sixteen primary 

 septa ; one of these is shorter than the rest, and occupies a non-prominent 

 septal break. 



The form is cornute and conical, with a tendency to become cylindrical in 

 the adult stage. The larger specimen has a length of 12 millimetres and a 

 calyx-diameter of 4 mm. 



Mr. Leach informs me that the larger specimen is from West Angle and 

 probably from the top of K 2 , and that the smaller specimen is from Fresh- 

 water West and from Z. 



These specimens appear to agree in essential characters with the description 

 of Cyatliaxonia comu given by Edwards & Haime, and may be tentatively 

 assigned to that species. 



Q. J. G. S. Xo. 246. z 



