Ten pairs of ribs are present. The first is much broader in the proximal half than in the distal half, but the distal end is slightly expanded. The first seven pairs possess both head and tubercle, but the eighth, ninth, and tenth have only a single terminal articular facet.
The sternum, which consists of five segments, is similar in form to that of semijunctus. The two sides of each segment are united. The posterior emargination of the third segment, and those of both ends of the fourth and fifth segments are small. The scapula and humerus are like those of semijunctus in form. The remaining parts of both pectoral limbs are lacking.
Without more material, and especially some skeletons of adults, it is difficult to decide what importance should be assigned to the differences observable in the cervical and thoracic vertebræ of this young Bering Island specimen. The measurements of the skeleton are included in the table on pages [47] and [48].
EXTERNAL CHARACTERS.
The series of photographs (Cat. No. 142579) of an individual obtained in Kiska Harbor, Alaska, is very interesting as affording comparison of what is apparently a specimen of grebnitzkii with the Atlantic form represented in the photograph of the Newport, Rhode Island, specimen. As no part of the Kiska specimen was preserved, it is not possible, of course, to identify it positively with grebnitzkii or even with the genus Ziphius. No one who compares the photographs reproduced in [Pl. 41], figs. 3 and 4, can, I think, fail to be convinced that both represent animals of the same genus and that the Pacific species (whether grebnitzkii or not) bears the strongest possible resemblance to the Atlantic one.
Doctor Egbert published the following note on the Kiska specimen in 1905:
Early in September a monster dolphin grounded on the beach in Kiska Harbor and was killed. Specific identification has not yet been made. The general color was bluish-gray; length, 18½ feet; estimated weight, 3,600 pounds; sex, male. Body was quite regular in shape and rather rotund, the greatest circumference being about midway between dorsal fin and tip of the rather short snout. This dolphin was hauled alongside the ship, stripped of its blubber, and the oil extracted. Some of the flesh was eaten. The oil obtained was of excellent quality. It was particularly desired for use on the wire of the deep-sea sounding machine used aboard the [U. S. Coast Survey steamer] Patterson.[47]
The size was about the same as that of the Newport specimen. Although Doctor Egbert gives the color merely as “bluish gray,” the photographs indicate that the belly was white, or whitish, and that there were oval white spots on the sides. As a whole, therefore, the coloration was similar to that of the New Zealand specimens of cavirostris obtained at Port Cooper and Lyttleton Harbor.
When compared with the photograph of the Newport specimen ([Pl. 41], fig. 4) it will be seen that the Kiska photograph represents an animal practically identical in general form, as well as in the general shape of the head, the length and form of the snout, the size and general shape of the pectoral fins. In the photograph of the Newport specimen the flukes are not well seen, but in the Kiska photograph the posterior median convexity peculiar to the ziphioids is clearly represented. The dorsal fin of the Newport specimen appears to be turned somewhat to one side and the tip crumpled, which makes it appear lower and somewhat longer and less pointed than that of the Kiska specimen. This may, of course, be a real difference, though such is probably not the case.
Considering the foregoing data relative to grebnitzkii as a whole, there is not in my opinion sufficient warrant at present for considering this form as a species distinct from cavirostris, and it should be added that no distinguishing characters were given in the original description.