R. G. Carruthers — A Revision of some Carboniferous Corals. 69 



Vertical Sections. — The tabulce are numerous, decidedly irregular 

 and vesicular in character, and are strongly arched in the centre of the 

 coral, with a well-marked depression at the fossula (PL V, Fig. 2). 

 Vertical sections cut clear of the fossula show a similar arrangement 

 of the tabulae to that seen in fossular sections, although the strong 

 upward bending in the middle of the coral is naturally not so apparent. 

 There are no dissepiments. 



Localities. 



Visean (Cg-S) : Hazelback (Caninia bed) and Arnside, apparently rare 



at both localities. 

 Tournaisian (Zg & Y) : many localities in the Bristol district (see 



Dr. ' Vaughan's paper, Q.J.G-.S. 1905), but especially at Big 



Weston Wood Quarry, Portishead (Z3), Cromhall (Zg & T), and 



Strawberry Hill, E. Clevedon (Zg). 

 The material at hand was not sufficient to adequately examine the 

 variation of this species, though the facts ascertained may not be 

 without interest. 



As regards shape, a definite division into three main groups seems 

 justifiable. These are sufficiently distinct to warrant separation, 

 although they do not merit varietal rank, for the septal characters 

 and arrangement in all three divisions are identical. They 

 may conveniently be referred to as (1) forvia tijpica, (2) forma a, and 

 (3) forma /3 (see Diagram D). 



Diagram D. — Outlines of Z. konincM, M.-Ed. & H. All half natural size. 

 1, forma typica ; 2, forma a ; 3, forma ;8. 



The first group {forma typica) exemplified in those specimens on 

 which the species were founded, is well represented in the Piret 

 Collection, and seems the common form at Tournai (an example is 

 given in PI. Y, Fig. 4), and may also be seen in specimens from the 

 Upper Tournaisian of the Bristol district, and from the lower Yisean 

 at Arnside ; the second group {forma a) is, as Dr. Yaughan has noticed, 

 the dominant form in the Bristol district,^ while the third group 

 •{forma /3) is found chiefly at Cromhall, near Bristol, and at Arnside 

 also. These growth forms do not seem to be of evolutionary value, 

 .and may perhaps be due to environment. 



As regards internal structure, some curious features are displayed 

 in a specimen from Tournai, in the Piret Collection (B. 11,677). 

 Externally, this specimen is of large size, with abundant strongly 

 marked constrictions of growth, giving a very corrugated aspect to the 

 ■coral. When sliced in serial transverse sections, it was apparent that 



1 Dr. Yaughan has figured an example in his Bristol paper (Q.J.G.S., vol. bd, 

 pi. xxii, fig. 3). 



