Specimens have never been recorded from the Pacific, but Captains H. G. Melsom and Fred Olsen assured me that they had seen bottlenoses along the northern coast of Japan not far from Aikawa. Whalemen of their experience who have hunted the animals in the Atlantic could hardly be mistaken, and I feel certain that before long specimens will be taken in Pacific waters. Whether or not they will prove to be specifically identical with the Atlantic bottlenose it is, of course, impossible to say. So far as present information extends there appears to be but a single species, the _Hyperoödon rostratum_, described by Müller in 1776. Because of the great changes which age and sex produce in color and in the shape of the head, numerous names have been given to individuals which have all proved to be specifically identical with the common form, _H. rostratum_. Although the bottlenose is the only commercially important member of the family Ziphiidæ, and is consequently the best known, the other species of this strange group are not less interesting. All the ziphioids are characterized by the tail which has no notch in the center and by the one or two pairs of teeth in the lower jaw, near or at the end, which sometimes develop in a most unusual way. In one species, Layard’s whale (_Mesoplodon layardi_), the two flat, strap-like teeth in the lower jaw grow upward to a height of eight or ten inches and sometimes bend over the long pointed snout, preventing the animal from opening its mouth more than an inch or two. How the whale feeds when the jaws are thus locked is a mystery. In one species, _Mesoplodon grayi_, besides the pair of functional teeth near the end of the lower jaw, a row of small teeth are present on either side, entirely embedded in the gum of the upper jaw. These never appear on the surface, even in the oldest animals, and are similar to the teeth concealed in the upper jaw of the sperm whale. In ancient times they were undoubtedly all well developed, but as the food of the whales changed, and the teeth became of less and less importance, they gradually began to disappear. The front portion of the skull of all the ziphioid whales is produced in the form of a long cylinder of bone which, although open in the middle in young specimens, gradually fills up by ossification of the central cartilage and eventually becomes of almost flinty hardness. Because of the extreme solidity of this portion of the skull it fossilizes very perfectly. When digging for the fortifications about the city of Antwerp hundreds of these bones and teeth were found, and many have been taken from the “Red Crag” deposits in England. Ziphioid whales are evidently an ancient group which was once very widely distributed. They are found today in the greatest numbers in the seas about New Zealand and Australia, but single specimens are continually appearing unexpectedly in almost every part of the world.