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CAPTAIN E. W. SHANN ON 
of this musculature ; but, through some mischance, the descriptions of his drawings 
are so inaccurate that they would be very difficult to follow without the corrections 
which I have ventured to make. 
The description of figs. 19, 20 is correct ; but in Hamburger’s “ Figurenerklarung ” 
the descriptions of these two drawings are inverted. 
On comparing fig. 17 with the statement in the text no agreement is found. The 
one muscle shown is marked M.b.r. 1, which the summarised description of this figure 
tells us is the basi-radialis internus ; moreover, that muscle takes origin on a bone 
denoted Bs. II. Examination of my own material shows that fig. 17 represents 
faithfully the basi-radiale internus — the distal portion of the adductor profundus ; 
it is thus a view of the dorsal (inner) aspect, not of the ventral as stated. The 
lettering of the radials (basalia) has been inverted in this particular figure, which 
accounts for the second discrepancy. 
The two muscles described as lying on the inner aspect of the fin in reality form 
the distal portion of the deeper abductor, or outer system, and are situated as shown 
in fig. 18. Here the text agrees with the summarised description, but both are at 
variance with fact. 
Hamburger divides the fin muscles, for practical purposes, into three systems 
based on their origins and insertions, but adds that they are divisible also, as in other 
Teleosteans, into an external and an internal system. The complicated condition of 
the fin musculature is fairly clearly derivable from the primary Teleostean condition ; 
they may be classified as follows : — 
Adductor (internal) System. 
I. Superficialis. 
1. Claviculo-radiale internus. 
2. Basi-claviculare internus superf. 
II. Profundus. 
3. Basi-claviculare int. prof. 
4. Basi-radiale internus. 
Abductor (external) System. 
I. Superficialis. 
5. Claviculo-radiale externus. 
6. Basi-claviculare ext. superf. i. 
7. Basi-claviculare ext. superf. ii. 
II. Profundus. 
8. Basi-claviculare ext. prof. 
9. Basi-claviculare transversus. 
10. Basi-radiale transversus. 
11. Opponens. 
To avoid confusion, Hamburger’s nomenclature has been retained ; though it 
must be remembered that here “ basi ” implies connection with the radials, and 
“radiale” with the fin rays or lepidotrichia, while references to the “ clavicle” are 
better stated in terms of the cleithrum. 
A fold of the preaxial radial grips and covers slightly superficially the claviculo- 
radiale internus, but this is not indicated in Hamburger’s illustration (fig. 16). The 
basi-claviculare internus superficialis, as Hamburger states, serves to extend the 
