258 PROCEEDINGS OF SOCIETIES. 



Pinnularia radiosa (fragment), (fresh water) ; Ballyleg Quarry. 

 Surirella minuta (fresh water) ; Ballyleg Quarry and Glenarm. 



„ subsaUa (fresh or brackish water) ; Ballyleg Quarry. 

 Synedra capitata (fresh water) ; Glenarm. 



„ radians (fresh water) ; Ballyleg Quarry and Portrush. 

 Tabellaria flocculosa, (fresh water); Ballyleg Quarry. 



„ fenestrata (fresh water); Ballyleg Quarry. 

 Tryhlionella marginata (fresh and brackish water) ; Ballyleg Quarry. 



In all, 42 different species, which may be distributed in the three 

 following classes : — 



Species found in fresh or brackish water, ... 4 



Marine species, 7 



Fresh- water species, 31 



Total, ... 42 



From this summary it appears that, as regards the number of spe- 

 cies found in these four specimens of chalk, there was a great preponde- 

 rance of fresh- water forms ; and the same observation applies to the 

 number of specimens belonging to each species. 



These facts I thought might possibly possess some interest, and, 

 therefore, I have not hesitated to submit them to the consideration of 

 the Section. I purpose following up this subject, and will publish any 

 further results in the " Transactions of the Dublin University Zoological 

 and Botanical Association." 



ANALYSIS OF CERTAIN ALLIED GENERA OF TERRESTRIAL ISOPODA ; WITH DE- 

 SCRIPTION OF A NEW GENUS, AND A DETAILED LIST OF THE BRITISH 

 SPECIES OF LIGIA, PHILOUGRIA, PHILOSCIA, PORCELLIO, ONISCTJS, AND 

 ARMADILLIUM. BY PROFESSOR JOHN ROBERT KINAHAN, DEPARTMENT OF 

 SCIENCE AND ART, M.B.T.C.D., M.R.I. A., HON. SEC. DUBLIN NATURAL 

 HISTORY SOCIETY, ETC. ETC.* 



Having been during the past summer engaged in researches among the 

 Irish Isopoda, I am induced to lay before your Association the results 

 to which I have been led by an examination of the above genera, — 

 the rather, as from authors this interesting family has received but little 

 attention, and in consequence but little is known with certainty con- 

 cerning the habits, species, and distribution of the group. This is the 

 more remarkable, as of the fourteen species now to be noticed, all, with 

 the exception of two, are of extremely common occurrence, and their 

 study, owing to their size, comparatively easy. In proof of this state- 



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

 1857. 



