58 BULLETIN 73, UNITED STATES NATIONAL MUSEUM. 



kept distinct on this account alone, at least until the character has been confirmed, 

 and perhaps strengthened by others, through the examination of a larger series of 

 specimens. 



SKELETON OF ZIPHIUS FROM BERING ISLAND. 



The Museum collection contains an incomplete skeleton of a very young indi- 

 vidual, Cat. No. 22875, which was received from Bering Island with the skulls of 

 Z. grebnitzkii, but does not belong to any one of them. Wliether it really represents 

 that species is, therefore, uncertain, but such is probably the case. The length of 

 the vertebral column, consisting of 45 vertebrae, without interspaces, is 9 feet 

 2 inches. 



The vertebral formula is as follows: C. 7; Th. 10; L. 10; Ca. 18 (+ 1?) = 45 (+ 1 ?). 

 This is the same as in the t3'pe of semijunctus so far as the cervicals, thoracics, and 

 lumbars are concerned, and the probable total is the same. In their general 

 characters these vertebrae agree ^\^th those of the skeletons already described, but 

 they present a number of differences as well. On account of immaturity the 

 processes are even less develoj^ed than in semijunctus. All the epiphyses are free, 

 and in the third to the seventh thoracic vertebrae the neural arch and spine are 

 separate from the centrum. The centra are very short in proportion to their width. 



Although the specimen is so young, the anterior foramen of the atlas is, never- 

 theless, inclosed by bone, and though the line of separation between the atlas and 

 axis is visible on the sides, the fourth cervical is anchylosed to the third at the top 

 of the centrum. Although the neural spines, metapophyses, and transverse proc- 

 esses of the thoracics are much shorter than those of the young semijunctus, the 

 epiphyses are as large or even larger than in that specimen. The neural arches are 

 also noticeably thicker than in semijunctus, and the centra are rounded inferiorly 

 rather than carinated. The neural spines are much more nearly erect than in the 

 adult Barnegat and Newport skeletons, but, as mentioned on page 41, this is 

 probal)ly a character of immaturity, and is shared by semijunctus. 



*The differences as regards the form of the centra and neural arches die away 

 among the lumbars, and these vertebra? and the caudals are, with a due allowance 

 for greater immaturity, very similar to those of semijunctus. 



The seventh thoracic is like the sixth in form, and is without a transverse 

 process. It thus resembles the same vertebra in semijunctus. The eighth, how- 

 ever, has an ill-defined facet on the side of the metapophysis and a second facet a 

 little above the upper border of the centrum. The eighth pair of ribs has only a 

 single terminal articular facet. 



The ninth thoracic has a short, thick transverse process, about in line with the 

 upper surface of the centrum. 



The transverse process of the seventh caudal is perforated on the right side by 

 a foramen. The transverse jjrocesses are last traceable on the ninth caudal, the 

 neural spines on the tenth caudal, and the neural arch on the eleventh caudal. 

 Eight chevron bones are preserved, but probably two more were present originally. 



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 



