57 
Since the description of Arceopom by Prof. H. A. Nicholson and the AVriter 
appeared, Messrs. Waagen and Wentzel have re-defined* the genus from material 
0 taiued from the rich beds of the Salt Eange in India, with the result that the 
characteristic of the genus must be changed to a certain extent in some points to fit 
Salt Range species.” Several points in their observations appear to call for remark, 
a the first place Arceopora is ascribed to Nicholson alone, as given in his “ Tabulate 
^ orals,” published in 1879. Messrs. AiTaagcn and Wentzel appear wholly to ignore the 
cading which they quote from this work as given by Prof. Nicholson, viz., “Arceopora, 
'TiT jon., 1879.” Secondly, the above Authors appear to be unacquainted 
o, or to have overlooked the description of Arceopora given by Prof. Nicholson and 
0 present AVriterjt which, as a matter of fact, was published before the “ Tabulate 
aig, and is the original and first published description of the genus. Had this not 
a So We should have referred, in ijreparing our joint memoir, to Prof. Nicholson’s 
a. Messrs. Waagen and AVentzcl, in the third place, state — “ No mention is made by 
ctiolson of the spongy condition of the walls of the corallites.” Not in so many 
i, perhaps, but in the expression “ porous condition of the walls,” used both in the 
abulate Corals ” and in our joint Memoir, far more is imi)lied than that the walls are 
’^ely pierced by mural pores. In addition, the figures gave an excellent idea of the 
pongy nature of the walls. Lastly, the Authors say — “ Another point which has to be 
ifieq condition of the tabula). They are well developed and quite distinct, 
rudimentary, in the Indian species.” What the tabula) may be in the latter it would 
presumptuous for us to say, in the absence of specimens ; but although they may be 
j, y ruarked in the Indian species that does not prove them to be anything else than 
imentary ia the Australian form. It is quite possible that amplification of the 
^^aracters of our genus may be required — as is usually the case in the first descriptions 
j J^^^eure fossils — ^but this hardly approaches the authoritative “ rectification ” 
^Smed by Messrs. Waagen and Wentzel. 
Type. 
Arceopora australis, N. and E. fil. 
AaiEoroiiA austualts, Nich. and Ulh. fil., PI. 3, figs. 6-9. 
a,usWalia, Nicholson and Eth. fil., Ann. and Mag. Nat. Hist., 1879, iv., p. 278, p. 279, f. 3 a, b. 
” It Nicholson, Tabulate Corals Pal. Period, 1879, p. Ifi7, f. 24 a, b. 
oOUal Clorallum massive, pyrifonn, of considerable size, composed of poly- 
t}jg prismatic corallites which radiate outivards from an imaginary axis to open on 
thr surface of the colony. Average diameter of the corallites from two-thirds to 
ordin' 9. line, no very small tubes being intercalated amongst those of 
'^^ensions. Walls amalgamated, irregularly cribriform. Septa variable in 
TltkerA irregularly dbdded. Tabulas rudimentary. {Nicholson and 
of ^^s. The corallum of A. australis might at first sight be readily taken for that 
^and^ larger and more massive species of Favosites (such as F. hemisphwricus, 
^he though even to the naked eye the absence of distinct tabulae and 
striking features. Our only 
porous condition of the walls are 
Wifj^ perfect, aud is not only completely silicified, but is thoroughly infiltrated 
its 
fj tinged with oxide of iron. Its height is rather more than 3 inches, and 
tiavin width something over 4 inches. Its form is pyriform, the narrow base 
almost ^^"^'■^®^^tly been attached to some foreign body, while the under surface was 
certainly covered by an epitheca, of which no traces now remain. The calices 
* Palaeontologia Indica, Ser. xiii., Pt. i.. No. 6, Coelenterata, p. 
+ Ann. and Mag. Nat. Hist., 1879, Vol. iv., p. 277. 
837 . 
