41 



shire, and that the direction of tbe wind over these counties during 

 the time was chiefly N. and E.N.E. At many places the day was 

 fine and bright. 



'•The change of wind from S. nearly to S.E. by midnight on the 

 14th, and to N.E. at about the time the fall began, and the change 

 of wind just before the rain ceased to indicate that this 



great fall of rain in so short a time was attributable to the meeting 

 of two currents of air of different temperatures, and the consequent 

 great deposition of moisture. 



" It will be seen that the weather in Ireland on this day was for 

 the most part fine. 



" I am, dear Sir, 



" Yours very faithfully, 



James Glaisher." 



" P.S. The average fall of rain in the month of ^larch is about 

 1*7 inch." 



.S'. H, Christie, Esq.. 

 Sec. R. S." 



April 3, 1851. 



LIEUT.-COLONEL SABINE, R.A., V.P. & Treas. in the Chair. 



A paper was read, entitled " Observations upon Appendicularia 

 and Dolioluray Bv Thomas H. Huxley, Esq. Communicated bv 

 E. Forbes, Esq., F.R.S. Received Feb! 26, 1851. 



This is a description of two Ascidian genera which possess very 

 considerable interest : DoVwlum, as forming a link between the 

 Pyrosomata and SalpcB ; and Appendicularia, as representing in a 

 permanent form the larval state of the Ascidians, long ago described 

 by M. Milne-Edwards. 



Appendicularia, which has been also imperfectly described under 

 the names of Oikopleura and Venillaria, is in fact an ascidian pro- 

 vided v/ith a long vibratile fin or tail, by the aid of which it swims 

 freely about. 



That it is an adult form is shown by the existence of a w-ell- 

 developed testis, but the author leaves undecided the nature of the 

 female organs. 



On the other hand it seems doubtful whether Doliolum is truly an 

 independent form, or whether it is not rather a detached " zodid " 

 of the genus Auckeiiia. 



A paper was also in part read, entitled Researches into the 

 Molecular Constitution of the Organic Bases." Part II. By A. W. 

 Hofmann, Ph.D. Communicated by Professor Graham, F.R.S. Re- 

 ceived March 12, 1851. 



