The great whale of the north, the Mysticetus, which our northern neighbours discovered while seeking for an eastern passage to India, a species which never leaves
the ice, carries no cirrhipedes. This fact was already known to Iceland fishermen of the twelfth century. The intrepid whalers of these regions used to distinguish a northern whale, without “calcareous plates,” from a southern whale with plates, that is to say, with cirrhipedes. This latter whale is the celebrated species of temperate regions, the Nord-Kaper which the Basques used to hunt, from the sixth century, in the Channel, and which they used afterwards to pursue even to Newfoundland. The whales of the southern hemisphere, like those of the Pacific Ocean, all have their own species of cirrhipedes. We found in the museum of the Zoological Garden at Amsterdam, a Coronula, brought from Japan by Mr. Blomhof, known under the name of Coronulæ reginæ, which, no doubt, characterizes the whale of those latitudes. Another northern whale, the Keporkak of the Greenlanders, very remarkable for its long fins, which give it the name of Megaptera, is covered very early in its life with these crustaceans, so much so, that the Greenlanders imagine that they are born with them. Some even have pretended to have seen Megapteræ covered with these coronulæ before their birth. Eschricht has in vain offered a reward to him who would send him coronulæ still attached to the umbilical cord; he has only received some pieces of skin covered with hairy bulbs. There is no doubt that young whales have been seen and captured while following their mother, which were already covered by these crustaceans.
Steenstrup has indicated the presence of Platycyamus Thompsoni on the body of the Hyperoodons, and the Xenobalanus globicipitis on the globiceps of the Shetland Isles.
The Cryptolepas is a new genus of Coronulidæ which
inhabits the coast of California, on the singular mysticete recently distinguished by the name of Rhachianectes glaucus. The Platylepas bisexlobata has lately been observed on one of the Sirenia, the Manatus latirostris. The marine turtles are also invaded by these singular animals, and their peculiar form, joined to their habitat, has given them the name of Chelonobia. It is not uncommon to find by the side of these Chelonobiæ, and even upon them, the Tanaïs, Serpulæ, and Bryozoariæ, forming together an animal forest on the cuirass of the turtle. The Matamata, a turtle living in the brackish water of Guiana, is covered with a cirrhipede more allied to the ordinary balani than to the chelonobiæ. Other living reptiles are not more exempt from cirrhipedes than turtles; the Dichelaspis pellucida and the Conchoderma Hunteri invade different sea-snakes. Many sharks harbour particular kinds, among which we mention the Alepas of the Spinax niger from the coasts of Norway. The same Alepas has been found on the Squalus glacialis at the same time as the Anelasma squalicola. Half a dozen varieties of these are known, one of which inhabits an echinoderm, another a decapod crustacean. These kinds of alepas are so reduced when they are adult, and are so completely despoiled of their distinctive attributes, that it is necessary to study them with especial care in their first dress, in order to recognize their parentage.
Other cirrhipedes establish themselves on neighbours of their own class, and we also find crustaceans upon other crustaceans. A pretty genus lives near Cape Verd on the carapace of a large lobster, and spreads itself on the centre of the back like a bouquet of flowers. My son has procured some very fine specimens, an
account of which he will publish, together with the other materials which he has collected during his passage across the Atlantic. Mr. John Denis Macdonald found in abundance on the branchiæ of a crab in Australia, the Neptunus pelagicus, which he places between the Lepas and the Dichelaspis.
The most singular, if not the most interesting of all these cirrhipedes, are the Gallæ, which appear under the tail of crabs or the abdomen of paguri, and which zoologists designate under the names of Peltogaster or Sacculina. They are found in both hemispheres. The recurrent development is so complete, that we can no longer distinguish any organic apparatus unless it be that of reproduction, and the whole body is a mere case enclosing within its walls eggs and spermatozoids. We see them very frequently under the abdomen of the crabs of our coasts, or even on the segments of the bodies of paguri. Mons. A. Giard has lately studied these animals. It is during the coupling season, according to him, that the Peltogasters establish themselves upon the crabs. Professor Semper has brought back quite a collection of them from his voyage to the Philippine Islands, and has entrusted them to one of his pupils, Dr. Kussmann, for the purposes of study. We heard him with great interest, at the late Congress at Wiesbaden, explain with remarkable clearness the results of his learned and conscientious observations. We do not think that we shall be wrong in adding that, for a long time, we shall see nothing better or more complete on this subject. All those cirrhipedes which adhere by their head to the skin of their host, by means of filaments, are now designated by the name of Rhizocephala.
A curious opinion, quite recently expressed by a naturalist, Mons. Giard, and which is a sign of the times, is that the Peltogaster of the Pagurus has become a Sacculina on the crab; the host having been transformed, its acolyte has done the same thing under the same influence.
Professor Semper has also found among the Philippine Islands, isopod crustaceans living as messmates after the manner of the peltogasters. Two cirrhipedes of the family of Peltogaster, the Sylon Hippolytes and the Sylon Pandali, have been found by Mons. Sars under the abdomen of the Pandalus brevirostris.