188 Prof. F. M^Coy on some new Carboniferous 



periments upon the influence of pressure, heat and electricity ; of 

 sulphuric, nitric, muriatic and hydrosulphuricacids; potash, ammo- 

 nia, alcohol, aether, turpentine, common salt, Owen^s liquid, milk, 

 fresh water. With very dilute sulphuric acid, the excitation is 

 strongly marked, attended with a rupture more or less rapid of 

 the filaments uniting the interior mass to the envelope, and finally 

 a detachment of the mass from the envelope, and a withdrawal 

 towards its mouth. A portion of the inner mass and tissues may 

 still cover the inner surface of the envelope ; but after a while 

 they come away from the envelope, and collect about the mouth, 

 leaving the envelope empty. In the dark there is a very brilliant 

 light at the first contact of the dilute acid with the Noctiluca ; 

 then afterwards there appears a clear fixed white light on one 

 part, which rapidly spreads, till the whole is like a ball of silver. 

 The brilliancy soon after begins to diminish, and rather rapidly 

 disappears. The rupture of the fibres and disorganization of the 

 interior mass evidently take place consentaneously with the 

 flashes and change in the light. 



It is hardly necessary to cite the other experiments in this 

 place. M. de Quatrefages concludes that the light is produced 

 by the contraction of the interior mass of the body; that the 

 scintillations are owing to the rupture and rapid contraction of 

 the filaments of the interior, and that the fixed light which these 

 animals emit before dying, proceeds from the permanent con- 

 traction of the contractile tissues adhering to the inner surface of 

 the general envelope. The production of the light is independent 

 of all material secretions. Ayiiether it is accompanied by a dis- 

 charge of electricity or not remains to be ascertained. 



XXII. — On some new Carboniferous Limestone Fossils. By Fre- 

 derick M'CoY, F.G.S., Hon. F.C.P.S., Professor of Mine- 

 ralogy and Geology in the Queen^s University of Ireland. 



Pinna spatula (M'Coy). 



Desc. Valves very narrow and much elongated, about four times 

 larger than the width of posterior end, very slightly convex 

 except at the beaks, which are pointed and almost cylindrical, 

 the sides gradually flattening as they approach the posterior 

 end, which is subtruncate or slightly rounded obliquely ; car- 

 dinal margin slightly thickened, with the cartilage ridge very 

 close within its edge ; surface perfectly smooth, or with very 

 faint laminar lines of growth parallel with the margins. 

 Length of large, rather imperfect specimen 5| inches, propor- 

 tional greatest width at posterior end about y^^^^, greatest 

 depth j-f^ or ^^^. 



