CORALS FROM BRITISH DEVONIAN BEDS. 505 
leading character upon which the generic name was founded (Za- 
gpev7ts “ strongly-floored’’). Correlated with this, we have (2) 
well-defined septal characters, notably the fact that, except near 
the periphery, their continuity as vertical plates is arrested by the 
floors, on the upper surfaces of which they only rise as crests. But 
this is not all; (8) the rudimentary condition of the secondary septa, 
taken in conjunction with (4) the almost complete absence of 
vesicular endotheca, forms a signal instance of correlation of struc- 
tures. The only approach to the latter condition is an occasional 
marginal subdivision of a tabula, usually with an outward dip*. 
Lastly, there are (5) the septal fossula and other signs both external 
and internal of bilateral and, more rarely, of quadripartite symmetry. 
Though so strikingly developed in Zaphrentis, these characters are 
very feeble in Amplexus, whilst, on the other hand, they are shared 
by many Cyathophylline and Axophylline, as well as the Diplo- 
cyathophyllide of Mr. Thomson. 
So far within the theca: the external characters are well known 
from better examples than any I can produce from Devonshire; and for 
this reason the word ‘‘ costee”’ does not once appear in the descrip- 
tions. J can only describe what I see. ‘The “ apertural gap” of 
Rominger, with coste pinnate on both sides of a parallel pair, the 
“lateral gaps” with pinnate coste meeting parallel ones,—these 
and other characters are fully set forth by Rominger, Dr. Duncan, 
and others. 
Whatever corals fail to satisfy the above conditions should, in my 
opinion, be excluded from the pale of the Zaphrentide, how long 
soever they may have kept their place on sufferance rf. 
The Zaphrentide perhaps exemplify the salient characters of the 
Rugosa more than any other family, except only Lindstrom’s “ oper- 
culate corals” with their strange angular forms. They stand far 
apart from those Cyathophyllide which, according to Dr. Duncan, 
pass by insensible gradations into the great class Aporosa of sub- 
sequent ages; but that they are the skeletons of Hydroid, and not 
_ Actinoid polyps, I cannot for a moment bring myself to believe, 
although this opinion is held by so high an authority as Agassiz. 
In conclusion, my best thanks are due to Messrs. Ktheridge, 
senior and junior, for the ample assistance and valuable hints they 
_ have afforded me, and the free use of any British-Museum specimens 
_ bearing on the subject. 
_ * Contrast with this the multitude of vesicles filling the interseptal loculi in 
- corals whose secondaries attain, say, half or more of the length of the primaries, 
as in the Cyathophyllide, Axophylline, &. This, agair, is correlated with a 
proportionate restriction of the tabule to the central area, a restriction that 
_ sometimes approaches the vanishing point. 
_ tT have just for the first time studied Zittel’s beautiful ‘Handbuch der 
- Palaontologie,’ and observe that the above opinion as to the partial dismember- 
ing of the Zaphrentidze has been forestalled. The genus Hallia, which was 
especially before my mind, has been placed under the head Pleonophora (the 
second subfamily of Diaphragmatophora, Dyb.); and the discoid genera of 
which Hadrophyllum forms a type, have been placed under the family Palzo- 
cycline. 
