256 PROCEEDINGS OF SOCIETIES. 



slightly developed. Mr. Macgillivray also points out what he considers 

 a difference in the feet, hut this is a mere difference in different indivi- 

 duals of different sizes. 



On the whole, then, the conclusion, I think, to he arrived at is, that 

 neither in the size, shape of bill, nor of feet, is there any other but an 

 accidental, or rather temporary, difference between a specimen of the one 

 species and a specimen of the other, these differences existing invicem 

 first in one and then in the other, but that the larger eye, and the 

 distinct line from the eye, joined to the wider and distinct rim round 

 the eye, are actual and permanent differences, and mark the species as 

 distinct 



DIATOMACE^J OCCURRING IN CHALK.* BY THE EEV. EUGENE o'MEARA, A.M., 

 MEMBER OF THE DUBLIN UNIVERSITY ZOOLOGICAL AND BOTANICAL ASSO- 

 CIATION. 



On the occasion of a recent journey along the coast of the county of 

 Antrim I visited an extensive quarry of white limestone, or chalk, at a 

 place called Ballyleg, on the road between Carrickfergus and Larne. As 

 I gazed upon the numerous strata, piled one upon the other to the height 

 of more than 100 feet, I thought how many myriads of diatomaceous 

 forms may have lain buried in these rocky sepulchres for thousands of 

 years, and felt a determination to try if I could disinter them. Accord- 

 ingly, I procured a specimen of the chalk from a depth of about 120 feet 

 below the summit of the cliff. A second specimen I took from the cliffs 

 at Glenarm; a third from Garron Point; and a fourth from the white 

 cliffs between the Giant's Causeway and the village of Portrush. 



Having in the first instance washed the specimens well for the pur- 

 pose of removing such forms as might have been attached to the surface, 

 I dissolved them separately in hydrochloric acid, the vessels used in the 

 process having been carefully rinsed. 



The chalk from the Ballyleg Quarry, having been so dissolved, was 

 boiled over a spirit-lamp, in dilute sulphuric acid, for about half-an- 

 hour, and the acid having been removed by repeated washings with 

 water taken directly from the pipe, and allowed to settle for some time 

 before it was used, a small portion of the sediment was mounted in the 

 usual way with Canada balsam. 



The other specimens having been dissolved in hydrochloric acid, and 

 washed in distilled water, were mounted in balsam, without any further 

 preparation. 



Having described the process, I come now to speak of the result. 



* Read before Section D at the Meeting of the British Association, Dublin, August 26, 

 1857. 



