Dioplodon sechellensis.
Inhab. Seychelles. Mus. Paris. Lord Howe’s Island (Krefft).
The form of the lower jaw gives a very peculiar appearance to the skeleton. The cervical vertebræ are united together by their bodies and large dorsal spines, the latter forming a thick conical process. The bodies of the dorsal vertebræ are very small, enlarging in size towards the tail; they are thirty-six in number. The four terminal caudal ones are very small, forming a kind of cylindrical process. There are eight chevron bones. The thoracic cavity is small. There are twelve ribs on each side. The dorsal processes of the first eighteen vertebræ have an anterior basal process, which becomes gradually smaller.
Upper arm-bone very slender, slightly curved; the lower arm-bones moderate, straight, parallel to each other, and rather longer than the upper arm-bone. The ribs very broad at the upper end, and gradually tapering towards the chest, where they are nearly cylindrical.
“The total length of the skeleton, without cartilage, is 14 feet 8 inches; the head measures 2 feet 5½ inches in length, and the lower jaw 2 feet 3 inches in length. The first three cervical vertebræ are anchylosed; the next one is more or less free; and the remaining three are anchylosed again. The dorsals are ten in number, the last bearing a short rib 8 inches in length. Five of these ribs are jointed direct to the sternum; the following two meet the cartilage of the fifth rib.
“The sternum is composed of four pieces, 20 inches long, with a width of between 5 and 7 inches. It is not yet sufficiently cleaned to enable me to have it photographed; this, however, will be done as soon as possible, and copies forwarded to the Society. The lumbars number twenty, the last nine having V-bones attached. The fifth lumbar is 17½ inches high, 4 inches wide at the top, and 11¾ inches at the base, including the side processes. The eleventh lumbar is the widest, being 4¾ inches at the top. The caudals probably amounted to 13; but five of these are missing; the basal one is very small, about the size of a pea; and as it was firmly attached to the second last, there can be no mistake about it.
“The head is 2 feet 5½ inches long and 14 inches across at the widest part; the lower jaw 2 feet 3 inches long and 6¼ inches high behind the tooth. The left tooth measures 6 inches in length, 3⅜ inches in width, and is 1¾ inch thick [not well represented in the figure]. The space between the teeth measures 7¼ inches. The limbs are very imperfect; all the smaller bones are missing; and there is only a part of one scapula. I did not find the pelvic bones.
“This animal was captured about a year ago, near Lord Howe’s Island.”—Krefft, P. Z. S. 1870, p. 426.
THE END.