On both sides of the Pacific the migrations take place at almost the same time. Along the Korean coast near the end of November single pregnant females appear, traveling steadily southward; a little later both males and females are seen; and finally only males bring up the rear, all having passed by January 25th. When going south almost every female is found to be carrying young nearly ready for birth, and all are hurrying straight ahead as though anxious to arrive at the breeding grounds as soon as possible. The devilfish again pass Ulsan, Korea, on the northward trip, about the middle of March, and by May 15 have disappeared. A comparison of these observations and those made by Scammon on the California coast show that the migration periods of both herds correspond closely and that the breeding grounds are in very nearly the same latitude. [Illustration: The flukes of a gray whale. The edge of the flukes of this species is very thick, but in most whales it is exceedingly thin. ] As yet it is impossible to state whether or not the Korea or California herds mingle in the north during the summer. Information gathered from the whalers tends to show that a large part of the former school summers in the Okhotsk Sea, and a large part of the latter in the Bering Sea and farther north. Individuals of the two herds may mingle and interbreed during their sojourn in the north, but it is probable that whales which have been born near either the Korea or California coasts will find mates among the members of their own herd during the southern migration, and return annually to their birthplace. It is quite conceivable that the case of the gray whale may be like that of the fur seal, where it has been shown conclusively that members of the American and Japanese herds do not mingle in the north although separated by comparatively few miles of water. Because of its regular migrations, the period of gestation of this species can be more nearly determined than that of any other large whale, and is about one year. Mating appears to take place in the south during December or early January, and the calf is ready for delivery at the same time the following winter; probably calves are born but once in two years. The length of the gray whale calf at birth is between twelve and seventeen feet and undoubtedly its size is much more than doubled during the first year after birth. The devilfish is a shore-loving species and on its annual migrations always prefers to cruise along close to the beach. When unmolested it swims about four or five miles an hour and cannot exceed nine miles even when badly frightened and doing its best to get away. At times the whales will go in so close to the shore that they are actually rolling in the surf, and seem to enjoy being pounded by the breakers. Scammon has observed the same habit in the California specimens and says: [Illustration: