The other well-defined _Squalus_ of the ancients is the _zygæna_ of Oppian, the Marseilles Jew-fish, the Balance-fish, the Hammer-fish, and were these not aliases enough already, the T-fish might be suggested as an appropriate synonym to add to the rest, the form of this letter suiting the outline of the fish to a tittle. The down stroke represents the body, and the horizontal bar at top the singular transverse head, at the opposite extremes of which two very salient, yellow eyes are situated, commanding from their position an extensive field of vision. When any thing occurs to ruffle the temper of the savage monster, these jaundiced eye-balls suddenly change to a blood-red hue, and roll, furiously glaring, in their projecting orbits; the portal of the mouth opens, and a huge, human tongue, swollen, inflamed, and papillated, surrounded by a whole armory of rending teeth, is thrust forth, presenting to view a creature so strange, hideous and malevolent, that nothing in nature can be compared to him. The domestic circle of the _Squalus zygæna_ numbers every year twenty-four new members; this fearful fecundity of the mother is providentially kept in check by the violent decease of most of the young in cunabulis, for these little cacodemons, untaught by their parents or Dr. Watts to consider it at all “a shameful sight for _Squali_ of one family to snarl, and snap, and bite,” commit the most cold-blooded fratricides, and even eat one another, _proh pudor_! without any remorse; besides this, when grown-up relations come on a visit, the young set are not secure from “battle, murder, and sudden death,” for a single moment, save when directly under the paternal nose; as a natural consequence, few of the nefarious brood survive childhood, or ever attain to full maturity of size and malice. Of such as escape infantine dangers, many in after life fall victims in hostile encounters with larger congeners; in particular with the white shark. The average length of the _S. zygæna_ is only eight or nine feet, but he does not fear to confront the powerful Requin himself, and fight him, too, with such pluck, resolution, and fury, that though the greatly superior weight of the other at length prevails, the victor does not leave the bloody battle-field scatheless, but like a second Pyrrhus, with the conviction that one more such conquest would undo him. We never saw any of these sea-termagants alive and in action, and must therefore refer the reader for full particulars to M. Lacepède, who had that advantage; but to judge from sundry recently dead specimens, with fins down, tail at rest, the hammer head resting on the pavement, and one eye only to be seen at a time, she was quite ill-looking enough to justify belief in all that biographers have recorded against her.