Genus MESOPLODON Gervais.
Of this genus the National Museum has four specimens; namely, (1) a skull (Cat. No. 21112, U.S.N.M.) obtained at Bering Island, North Pacific Ocean, in 1883, by Dr. L. Stejneger, and made the type of the species M. stejnegeri True; (2) a skull and photographs (Cat. No. 143132, U.S.N.M.) of the same species, from Yaquina Bay, Oregon, obtained in exchange from Mr. J. G. Crawford in 1904; (3) a skeleton, cast, and photographs of a young male (Cat. No. 23346, U.S.N.M.), hitherto supposed to represent M. bidens, caught at Atlantic City, New Jersey, in 1889; and (4) a skeleton of an adult (Cat. No. 49880, U.S.N.M.) from the Chatham Islands, New Zealand, representing M. grayi.[1]
In addition to this material, I have had the privilege of examining two skulls belonging to the Museum of Comparative Zoölogy, and hitherto supposed to represent M. bidens, and two skeletons belonging to the American Museum of Natural History. Of these last, one is that of an adult and was purchased by the American Museum under the name of M. layardi, but was subsequently recognized to be a new species and was described by Mr. Andrews, under the name of Mesoplodon bowdoini. The other is that of a young individual, and has been labeled M. grayi.
As already noted by Dr. G. M. Allen,[2] only four specimens of Mesoplodon have been recorded hitherto from the Atlantic coast of the United States. These are:
1. An adult, sex unknown, but probably female, 16 feet long, found at Nantucket, Massachusetts, in 1867, and recorded by Prof. L. Agassiz.[3] The skull of this individual is in the Museum of Comparative Zoölogy, Cambridge, Massachusetts.
2. A young male, 12½ feet long, captured at Atlantic City, New Jersey, March 28, 1889. The skeleton (Cat. No. 23346, U.S.N.M.) is in the National Museum.
3. A young female, 12 feet 2 inches long, stranded at Annisquam, Massachusetts, August, 1898, and recorded by the late Alpheus Hyatt.[4] The skeleton is in the museum of the Boston Society of Natural History.
4. An adult female, said by fishermen who measured it to have been 22 feet long, entangled in pound nets at North Long Branch, New Jersey, July 22, 1905, and recorded by Dr. Glover M. Allen.[5] The cranium of this individual is preserved in the Museum of Comparative Zoölogy. The rostrum and mandible, which were originally obtained, were afterwards destroyed by accident.
I have examined all this material. Writers who have had occasion to mention these four specimens thus far have referred them tacitly to Mesoplodon bidens (Sowerby), but, after a careful study of them, I have ascertained that while the Nantucket specimen belongs to that species, the Atlantic City and Long Branch specimens represent Mesoplodon europæus (Gervais). This is a very interesting discovery, because the latter species has been known hitherto only from a single skull, and its validity has been frequently questioned. The Annisquam specimen, as will be seen later, presents characters which appear to ally it to M. densirostris.