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 original composition has, to a great extent, been replaced by silica.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, Holtenia 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. I, 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 



