140 Mr Haldlnger on the Series of Crystallisation of Ajjatite. 
d, The dilatation found in the trachea of this bird, 
and formed simply by an increase in size of the natu- 
ral rings of the trachea. 
e, A remarkable osseous dilatation found at the di- 
vision of the trachea into the bronchial tubes. 
It has not been thought necessary to give a representation of 
the windpipe in the singing swan ; the peculiarity in the trachea 
of that bird consisting not in any dilatation of its caliber, but a 
great increase in length, beyond the actual measurement of the 
neck. It has been often described by authors. 
Art. XXIII. — On the Series of Crystallisation of Apatite. By 
WiLLTAM Haidinger, Esq. 
l^^IoST of the mineralogical systems of the present day, per- 
haps that of Werner only excepted, agree in a perfectly correct 
determination of the species of Apatite. In the system of Pro- 
fessor Mohs, it forms with Fluor-Spar a particular genus of the 
order Haloide ; and agreeably to this arrangement, apatite is 
termed the rliomholiedral.^ whilst fluor-spar receives the denomi- 
nation of the octahedral jiuor -haloide. When first introduced 
to the notice of mineralogists, it gave rise to a great contrariety 
of opinions. Unfortunately, the name of Chrysolite, given by 
German mineralogists to the species of prismatic chrysolite of 
Mohs, had been applied by the French to the asparagus-green 
varieties of rhombohedral fiuor-haloide from Spain, the Spargel- 
stein of Werner; and the great confusion produced by this 
double employment of the same name had not ceased before that 
of chrysolite had entirely been expunged from the French mi- 
neralogy, and in the German, finally given to that species which 
is denominated Peridot by Haliy. One of the varieties of apa- 
tite, found at Johanngeorgenstadt in Saxony, was, for a long 
time, exhibited among the varieties of precious beryl ; afterwards 
it was called Agustite, when, by some imperfect analysis, it was 
supposed to contain a particular kind of earth, the agust-earth, 
so called, on account of the property of forming insipid com- 
pounds with several acids, vdiich substance, however, subse^ 
