The beak is made up of horny elements, like the labial teeth, fused together; its edge, when sufficiently magnified, is seen to be denticulate, each denticle representing the cusp of a single tooth.

On the other hand, in Merycopotamus, of the Lower Pliocene of India and Burma, the upper molars have lost the fifth intermediate cusp of Ancodon; and thus, although highly selenodont, might be easily modified, by a kind of retrograde development, into the trefoil-columned molars of Hippopotamus.

The branch, whether re-entrant or infinite, may have a cusp or cusps, or it may cut itself or another branch, thus having or giving rise to crunodes or double points with distinct real tangents; an acnode, or double point with imaginary tangents, is a branch by itself, - it may be considered as an indefinitely small re-entrant branch.

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The double point larities - cusp or spinode; or node; Line-singu5 3.

Today we are on the cusp of a substantially more profound shift in work life.

All four of us are kissing thirty, swinging on that cusp between frantic singles and life commitments.

As regards the so-called hyperbolisms, observe that (besides the single asymptote) we have in the case of those of the hyperbola two parallel asymptotes; in the case of those of the ellipse the two parallel asymptotes become imaginary, that is, they disappear; and in the case of those of the parabola they become coincident, that is, there is here an ordinary asymptote, and a special asymptote answering to a cusp at infinity.

But if the given curve has a node, then not only the Hessian passes through the node, but it has there a node the two branches at which touch respectively the two branches of the curve; and the node thus counts as six intersections; so if the curve has a cusp, then the Hessian not only passes through the cusp, but it has there a cusp through which it again passes, that is, there is a cuspidal branch touching the cuspidal branch of the curve, and besides a simple branch passing through the cusp, and hence the cusp counts as eight intersections.

X The involute of the catenary is called the tractory, tractrix or antifriction curve; it has a cusp at the vertex of the catenary, and is asymptotic to the directrix.

Each cusp of the primitive triangle has received a separate name, both in the teeth of the upper and of the lower jaw, while names have also been assigned to super-added cusps.