^12 ON THE GllOWTH AND STRUCTURE 
my notice ; and viewing the subject as one of general in- 
terest, I have ventured to call the attention of the Society 
to the following brief history of these organs. 
All anatomists are aware that the serpents called poison- 
ous possess two kinds of teeth ; viz. numerous simple teeth, 
implanted in rows into the lower maxillary bone, and into 
the palate-bones of the upper jaw, — and, in certain species, 
to be described afterwards, into the upper maxillary bone 
itself ; these are employed by the animal in laying hold of 
its prey. These teeth have, I believe, generally been con- 
sidered permanent ; but this opinion I do not consider cor- 
rect, because they are found to vary in number even in the 
same varieties, and because I have observed unattached 
simple teeth in the rattle-snake, — -that is, simple teeth of 
rather a soft texture, placed obliquely betwixt the fixed 
teeth, and attached to the maxillary or palate bones by soft 
parts only. 
In several innoxious snakes now lying before me, there 
exist two distinct rows of simple teeth, attached only by 
soft parts to the maxillary and palate bones, running pa- 
rallel with those already fixed into the bone. These sup- 
plementary rows of teeth are placed internally with regard 
to the fixed ones in the maxillary bones, but externally to 
the same in the palate-bones. They seem to me in a per- 
petual state of growth, and advance to supply the place of 
those which the animal casts by a regular process of nature, 
analogous, no doubt, to the mode of dentition so long ago 
observed in certain fishes, as the shark, &c. Moreover, the 
lower maxillary and palate bones, around the bases of the 
tooth, have the same loose, cellular and vascular appear- 
ance as that portion of bone to which the fangs are attached, 
and which will be described more particularly in a future 
part of the paper. A section of the jaw-bone demonstrates, 
thaj, when once the tooth has become fixed, its mode of 
