﻿Vol. 6 1.] SEQUENCE IN THE BEISTOL AREA. 271 



by Edwards & Haime as an important diagnostic character ; "but I 

 have collected, from the same bed, specimens in which the fossula 

 is as often on the short side of the horn as on the longer one : 

 whereas, in all the specimens, the characters of the septa and tabular 

 are identical. 



ZapJirentis GriffitJii agrees with our forms in all the essential 

 characters of septal grouping and tabular flexure, and only differs 

 in its short and broad form and in its more numerous septa. 



ZapJirentis Phillipsi (Edwards & Haime), Thomson, is illustrated 

 by a very inadequate figure. Erom the author's description, it is 

 evident that the form with which he deals differs markedly from 

 ours in the following characters : — 



The septa are thin, and pointed towards their inner ends. 

 Three of the septa extend into the fossula, of which the central one is 

 considerably the shortest and not more than half a line in length. 



Zapheentis aff. coenttcopi^e (Mich.), 1 Edwards & Haime. 

 (PI. XXII, figs. 3-3 d.) 



Prox. ZapJirentis cornucopia, Edwards & Haime, ' Polypiers Foss. Paleoz. 

 p. 331 & pi. v, figs. 4-4 a. 



Eorm : elongate, cornute. The average length is between 3 and 

 4 centimetres. Epitheca with indistinct rugse and a few distant 

 constrictions. Calyx circular, deep and cup-shaped, with bevelled 

 rim. 



Primary septa strongly thickened at the wall, 35 to 40 in 

 number, close and very regularly spaced, so that the symmetry is 

 strikingly radial. 



Secondary septa short and thick, just projecting beyond the 

 thick wall. Wall dense and thick, being formed by the thickening 

 of the ends of both series of septa. 



Septal breaks and fossula. — The only conspicuous break is 

 the fossula, which extends from the centre to the wall of the coral, 

 and is bounded by vertical walls ; in cross-section, it is slit-like 

 and typically keyhole-shaped. 



The fossula is open throughout its length, but, near the outer wall, 

 it is constricted by the elongation of two secondary septa, which 

 bend round and become united with its lateral walls ; a single 

 rudimentary primary septum projects for a very short distance into 

 the fossula. The fossula is, in every specimen that I have seen, 

 on the side of the longer curve of the horn. 



Two inconspicuous lateral breaks are usually indicated by the 

 elongation and bending of a secondary septum on each side. 



In the very young form, the structure approximates to that seen 

 in ZapJirentis aff. Phillipsi ; the horizontal section is bisected by 

 the meeting of the two terminal septa of the antifossular group, 



1 The figure given by Michelin, ' Icon. Zooph.' pi. lix, fig. 5, is characterized 

 by Edwards & Haime (' Monogr. Brit. Foss. Cor.' pt. iii, p. 167) as a very bad 

 figure ; it agrees better, however, in elongated form, with the specimens common 

 in the Bristol area than does the figure in the ' Polypiers Foss. Paleozoiques.' 



