74 
Wright— List of Irish Cretaceous Microzoa. 
the North of Ireland, and in addition, through the kindness of Mr. Wm. Gray, 
M.R.I.A., Mr. S. A. Stewart, F.B.S.E., and Mr. Thomas Galloway, have 
had an opportunity of examining Chalk powder from 36 different localities 
in the Counties of Antrim, Londonderry, and Down. Among the many 
specimens collected from these various places, I have recognised, besides Corals 
and Polyzoa, 17 species of Ostracoda, 106 species and well marked varieties of 
Foraminifera, and 27 forms of Sponge spicula; many of these attain fine propor- 
tions, being much larger than those usually obtained from the washings of English 
Chalk. The Microzoa, on being placed in hydrochloric acid, were found to 
be, either not at all, or but very slightly affected by it, shewing that their 
original composition has, to a great extent, been replaced by silica. On account 
of the singular resemblance which many of those large flints known as Para- 
moudras,” bear to the deep sea siliceous sponge, Holtmia Carpenteria , I was 
specially desirous to obtain material from some of them for examination. Owing 
to their usually solid nature, this was difficult. I met, however, with several 
that were suitable, so that I was enabled to investigate the contents of four 
Paramoudras that were fossiliferous. The following is an analysis of those 
in question : — 
No. 1, from Wolf Hill, near Belfast, 130 Spicula, 57 Foraminifera ; No. 2, 
from same locality, 130 Spicula, 8 Foraminifera; No. 3, from Ballytober, 
Islandmagee, 5 Spicula, Foraminifera in great numbers ; No. 4, from Sallagh 
Braes, near Larne, Spicula in profusion, Foraminifera plentiful. The above 
results show that there is no appreciable difference between the contents of 
Paramoudras and ordinary flints. Both contain Sponge spicula in more or less 
abundance, the “Paramoudras” not being characterised by any special form 
of spiculum, which the others do not also contain. The one examined from 
Sallagh Braes yielded nearly all the different forms of spicula found in our 
Chalk powder, and in this respect closely resembled what was found in a small 
ordinary flint at Spring Hill, near Moneymore, Co. Derry ; whilst the “ Para- 
moudra” from Ballytober, Islandmagee, though it contained Foraminifera 
and Ostracoda in abundance, had but very few spicula. From the general 
frequency of spicula in flints there cannot, however, I think, be any doubt but 
that most, if not all, of our nodular flints had their origin in a sponge, or 
some other soft organism round which the silica aggregated. 
The Table given at the end must be considered as only an approximation to the 
general distribution of the Cretaceous Microzoa over the districts examined, the 
absence of many of the commoner species at some of the localities may be readily 
accounted for when we consider the small quantity of powder in some instances 
obtained. Thus at Larne, and at Spring Hill, near Moneymore, only a few grain* 
of Chalk powder were found, several other localities also yielding but a very 
limited supply, whilst the flints at Woodburn quarry, as well as those on the 
shore between Blackhead and Gobbins, yielded, at a single visit, several pounds 
