und Wissenschaftliche Medicin, -c. 1 97 
are floated down by the stream. We think it very probable, that, although there 
may not be any striking difference in their internal organization, that in some 
points their structure may be modified to suit the peculiar economy, and adapt 
them to the necessities of their existence. The C. Rhombifer, in its internal 
structure, bears some affinity to the Ophidians. In general the circulation is lan- 
guid, and the volume of blood small in proportion to their dimensions. An illus - 
trative plate of the heart of C. lucius is given. 
The second article is from Dr C- T. Von Siebold of Dantzic, on the Sper- 
rnal Ducts of Crustacea, Insects, Gasteropodes, &c. with two explanatory plates. 
Dr Weber of Bonn contributes some very interesting observations on the hip 
joint and the theory of motion of the human step. 
Some notices on the anatomy of the windpipe of Anas leucocephalus and 
Ibis falcinellus, founded on observations made upon a set of preparations in spirit 
of wine brought from Sardinia by Mr Kiister, with other remarks on compara- 
tive anatomy, are given by Professor Wagner of Erlangen. 
The windpipe of a male of Anas leucocephalus. was found to have a widen- 
ing at the top, somewhat like that in Anas clangula, an inch and a-half long, 
below which the pipe is very narrow. 
In Ibis falcinellus (the common Ibis,) the lower rings of the windpipe are 
very small, thin and rather round. They run close together, but are not joined. 
From the whole circumference of the last rings a strong membrane springs, which 
binds the two bronchials to the windpipe. 
