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found which present themselves as flattened bands, pointed 
at the ends, and with the nucleus either entirely absent, or 
lying detached near the outer surface. Closer examination 
will reveal transition forms between the round and the 
flattened cells, as many may be observed which appear 
round towards one extremity and ribbon-shaped towards 
the other. A drawing is given of a fibre-cell the lower part 
of which is pale and flattened, whilst the upper part of the 
same is round, and marked with several colours. Between 
these two parts is a sharply-defined linear slit, which at the 
commencement of the round part of the fibre is bifurcated. 
The lateral portions of the fibre on each side of this slit 
become thinner as they pass into the lower or flattened 
portion. The ribbon-like form of one part of the fibre no 
doubt results from the change in position and shape of the 
lateral portions divided by the slit, which extends to the 
centre. The nucleus during these changes becomes detached 
from the muscular fibre, and is either altogether removed, or 
rests upon the surface. This superficial position of the 
nucleus is not the normal condition in the smooth muscular 
fibre of the bladder, as one may in transverse sections of 
fresh and uninjured muscle always readily observe one or two 
nuclei in the central part of each cell. 
Shei.l. — Professor King, of Galway, who has much right 
to speak with authority on the subject he discusses, treats of 
the Histology of the Test of the Class Palliobranchiata, in 
the Trans. Royal Irish Acad., vol. xxiv, 1869. He 
figures the perforations in many genera, and has some 
especially valuable remarks on Crania and Megerlia. He 
maintains that Syringothrysis cuspidata is not represented in 
an isomorphic genus, as maintained by Dr. Carpenter, on 
account of the supposed absence of perforations in a speci- 
men called .Spirifer cuspidatus, which was submitted to him 
for examination by Mr. Davidson. 
Professor Percival Wright, of Dublin, describes the 
Structure of Tubipora musica (the Organ-pipe Coral) in 
the Annals for May. He was successful in obtaining 
this polyp alive in his recent visit to the Seychelles. He 
describes the tube as formed by the agglomeration of fusiform 
and nodular spicules, which increase as growth proceeds, 
thus differing from Kolliker, who assigns a crystalline 
structure to the tube of Tubipora. 
Microzoology.— The Anatomy of Stentor and its Mode of 
Reproduction is described by Dr. Moxon in the Journal of 
Anatomy, May, 1869. He particularly opposes the view 
that the “ contractile vesicle ” of Infusoria forms part of a 
