ORIGINAL COMMUNICATIONS.
NOTE on the EXISTENCE of a PAIR of SUB-CUTANEOUS
ORIFICES in the HEAD of the EEL and CONGER. By the
REV. W. HOUGHTON, F.L.S.
HAVING been occupied at intervals during the last three
months in. dissecting a number of eels {Anguilla acutirostris)
and a couple of Congers, I observed the invariable presence
of two sub-triangular openings in the fleshy portion of the
head, just at its juncture with the spinal column. My first
impression with regard to the use of these orifices was that
they were connected with the auditory Organs, and that they
probably led to the yestibular cavity. Although so far, I
believe, as has hitherto been observed, the existence of
external auditory organs in the whole class of fishes is very
exceptional—the skates amongst the cartilaginous order,
and a few of the members belonging to the Gadidae and
ClupeidtB amongst the osseous order alone possessing them—
still I thought it not improbable that the eel, which is
commonly supposed to hear well, and which is occasionally
an overland traveller, might prove another exception to the
general rule. I may observe that Mr. Cholmondeley
Pennell, in his recently published work, 'The Angler
Naturalist 5 (p. 397), asserts the presence of an "ear or
auditory aperture " amongst the various mucus pores about
the head, but from the most minute examination of a large
number of eels' heads I can confidently aflirm that no such
external auditory aperture exists. I have, therefore, no doubt
that Mr. Pennell must have mistaken two of the mucus
pores for ears.
Upon my inserting a bristle in each of these orifices, and
on clearing away the flesh from the head, I found that each
bristle traversed a closed-in duct or tube in the cranium, and
VOL. IV.
NEW SER.
A
2
BECK, ON ILLUSIVE APPEARANCES.
came out just above the orbital bone (see PI. I,fig.1). On
making a vertical section of the skull, and examining with
great care the vestibular sacs, I became convinced that the
tubular ducts had no connection with them nor with the
auditory nerve (fig. 4). Each of these tubes, which in the
common eel is just wide enough to admit a fine piece of silkgutj terminates in a membranous fold or hollow in the subcutaneous tissue just above the eye (fig. 5), and contains a certainquantity of thin fluid or lymph, which, by the way, bears no
resemblance to mucus. Are these cavities reservoirs for the
supply of fluid to lubricate the surface, and may we conjecture
that the lymph is drawn up the tubular ducts by capillary
attraction ? There is little reason to doubt that the cranial
ducts are connected with the so-called " mucus system"
which is very complicated in the eel tribe, but in what
manner they are so I have hitherto been unable to satisfy
myself, and leave the determination of the question to the
investigation of more experienced anatomists.
On the ILLUSIVE APPEARANCES produced by some TRANSPARENT OBJECTS. By RICHARD BECK.
To view an object by passing light through it, or, as it is
commonly termed, to look at it as transparent, is a method
of examination not only peculiar to the microscope, but also
one to which the naked eye is quite unaccustomed. I t frequently conveys to the mind most imperfect ideas of an
object, and in very many instances it produces appearances
which even in shape bear no resemblance to the true
structure : of this fact, which is somewhat difficult of proof,
most conclusive evidence may be furnished by a careful
examination of the scales of Lepisma Saccharina.
This insect may be found in most houses, frequenting
damp warm cupboards, or as an associate in the dark of
black-beetles and cockroaches, and its scales have been long
known to microscopists.
The insect, which is very active, should be caught without
injury in a clean pill-box with a few pin-holes in the lid, and
a drop of chloroform over these holes will soon make the
inmate insensible, when it may be turned out upon a piece of
clean paper.