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LXIX. On the Structure of the poisonous Fangs of Serpents. 
By Tuomas Smirn, £sq. F. R.S.* 
Waren the poisonous fangs of serpents are attentively ex- 
amined, a slit or suture may be observed extending along the 
convex side, from the foramen at the base to the aperture near 
the point. (Plate V. A.B. C.D.) This isa consequence of an 
unusual, and hitherto, I believe, entirely unnoticed structure, 
resulting from the mode of formation of the tube through which 
the poison flows. 
My attention was called to this structure, by having lately 
received from my friend Mr. Herbert Ryder, the assay master 
to the mint at Madras, the bones of the’skull of a cobra de ca- 
pello. I had some years since noticed the slit running along 
the convex side of the fang, in making a preparation of the head 
of the common viper of this country, in which it is distinctly 
seen when magnified ; nevertheless, it seems to have been over- 
looked by all the numerous authors who have written upon the 
subject of the venomous fangs of the viper, and who, as far as 
structure is concerned, do not appear to have advanced beyond 
Pliny, to whom, and even anterior to whose time, the circum- 
stance of their being tubular was well known. 
All teeth being formed irom a pulp, which has the shape that 
the tooth itself is destined to retain, it has probably been ima- 
gined that the tube of the‘ poisonous fangs of serpents was pro- 
duced by a perforation. passing through the pulp; this is not, 
however, the case, the tube being completely external, and 
formed by a deep longitudinal depression on the surface of the 
pulp. 
In order to render this more clear, I must here observe that 
a slight longitudinal furrow, or depression, is to he seen on all 
the teeth of the cobra de capello; on those which are nearest 
to the poisonous fangs it is most evident, and occupies the con- 
vex side of their curvature; it however is confined entirely to 
the parietes of the tooth, and does not at all affect the form of 
its cavity. 
But in the poisonous fangs, this depression is sunk deep into 
the substance of the tooth, and occupies a portion of the space, 
which in the others is allotted to the cavity which contains that 
part of the pulp which remains when the tooth is completely 
formed; and the edges of the depression being brought together 
along the greater part of the tooth, form the slit or suture that 
I have before described, but, being kept at a distance at both 
extremities, there results a foramen at the base and at the apex. 
* From the Transactions of the Royal Society for 1818, Part I. 
That 
