Fig. 1. Mesoplodon bidens. Skull. Nantucket, Mass. Female, adult. Mus. Comp. Zoöl. No. 1727. Ventral aspect. About ¼ nat. size. Tip of beak, left pterygoid, and malars defective.
2. Mesoplodon densirostris? Skull. Annisquam, Mass. Female, young. Boston Society of Natural History. Ventral aspect. ¼ nat. size.
Left frontal region defective.
Plate 5 SKULLS OF MESOPLODON EUROPÆUS
Fig. 1. Mesoplodon europæus. Skull. Atlantic City, New Jersey. Male, young. Cat. No. 23346, U.S.N.M. Ventral aspect. ¼ nat. size.
2. Mesoplodon europæus. Skull. North Long Branch, New Jersey. Female, adult. Mus. Comp. Zoölogy. Ventral aspect. ¼ nat. size.
Distal portion of beak lacking, pterygoids, malars, and left frontal and temporal regions defective.
Plate 6 SKULLS OF MESOPLODON STEJNEGERI
