432 Scientifie Intelligence. 
fishes are extremely numerous, existing over the whole external sur- 
face. In freshwater fishes, and in those living in shallow waters, they 
are 2 copes few. hey are most numerous in fishes which swim 
sply to'a question of Dr. Wyman, he ats that he had not as yet 
hem in the sharks and rays. These openings are sometimes vis- 
‘ible to the ikea eye, and sometimes require a magnifying power for 
t their detection. They are very large and numerous, and easily seen, 
in the head of the common shad; These minute tubes unite into larger 
ones, in a manner which seems to be the same in each cla He 
thought this circumstance might be of. some value in the classification 
of fishes. The tubes grow larger and larger as they approach the 
Piven. se near the head or the tail, or in 
other parts of the body. He believes these tubes an apparatus for 
the safety of fishes living at great depths, to enable them ¥ _ the 
pressure to which they must there be subjected. He did not deny the 
existence of mucous tubes in fishes, for there are such, ee be heads 
of sharks for i instance, from which m mucus may be obtained by pressure; 
but: he i is sure, that what have been hitherto considered as mucous june, 
= in reality water tubes. 
Structure of the Foot in pele Birds, ( vid June 1 p. 42.)— 
Prof. Acassiz had recently made some observations on the structure of - 
the foot in the embryo of birds, whieh. Ne thought smeld: throw new light 
on, the sige sg ge of birds, and. sonnet 2 call for radical changes in 
the system now in use. He had’ examined the feet of the embryo of 
dus pit nictiee us, Hirundo riparia, Sylvia @stiva, and —— 
melodia, and found, the following appearances in all. 
four toes, which in»the, mature bird are separate, three bei ing di 
rected forwards: and o one backwards, are in this state - directed: faith 
wards, and webbed. . There is as yet no trace of bone in them; the 
are only rows of cartilaginous cells in the position to ws occupied by 
bone, which are more closely a together at the points where the 
joints are destined to appear. The ower extremity is, in fact, at ~ 
me, a fin. 
however, only three rows of cartilaginous cells, united by a mem nhiegne- 
As this-condition of the extremitiés exists in different families, Prof. A- 
thinks that the presént grouping of all’web-footed birds together, may 
be incorrect; particularly since they differ as much among themselves 
in other respectsvas they do from land birds. He fourid that the bill of 
the immature robin resembled that of a vulturine bird, being strai 
near the base, and curved at the’ extremity, the upper ‘mandible being a 
longer than the lower. This would seem to indicate that the vulturine 
form isa lower type than it ni usually been considered. This ap- 
peared to derive confirmation from the great resemblance of the pill of 
some of the water birds to that of some of the vulturine family, that of 
the genus ota rx for example. Some of the birds of prey also h 
