G9 



has, under favourable circumstances of observation, been more 

 or less visible. In order to witness it in perfection the fibre 

 must be on the stretch, for when it is torn from its attachments, 

 or lies relaxed in the bottom of the cell, the stria? become very- 

 obscure. When the broken extremity of a fibre is examined, 

 the fracture will be found to have occurred in a plane perpen- 

 dicular to the axis of the fibre, never exhibiting an uneven 

 or lacerated appearance, and a marked tendency to separate 

 into disks may be recognised in the detached and broken fibre. 

 When the fibre is in an uncontracted state it Avould seem to 

 be perfectly cylindrical, and the normal act of contraction ia 

 so momentary that its condition during this state cannot be 

 witnessed. When, however, the living polypide is torn from 

 its cell, the ruptured fibres, which continue attached to its body, 

 are thrown into a state of spasmodic contraction ; and then 

 it will be seen that they lose their cylindricity, and become ir- 

 regularly swollen at intervals, while the whole fibre has much 

 increased in thickness. In this condition also they may be 

 observed to be obscurely striated. The swellings here visible 

 in the contracted fibre are quite different from the peculiar 

 knots described by Dr. A. Farre in the muscles of the marine 

 polyzoa. Such knots do not exist in the fresh-water species, 

 at least I have never seen them, with the exception, perhaps, 

 of certain little swellings which may be occasionally witnessed 

 in the parietal muscles of Paludicella, and in the superior pari- 

 eto-vaginal muscles of Plumatella. In Paludicella I have wit- 

 nessed a curious phenomenon presented by the muscular fibre. 

 In this polyzoon the fibres of the great retractor muscle, while 

 lying relaxed in the bottom of the cell after the retraction of the 

 polypide, may frequently be seen to present a singular' motion, 

 impressing you with the idea of a cluster of writhing worms." 



Rev. W. P. Moore read a description of the Vitrified Font 

 of Shantamon, in the county of Cavan, and at the same time 

 presented specimens of the stone of which the font is composed. 



