BEAKED WHALES, FAMILY ZIPHIIDiE TEUE. 17 



The transverse processes of the himbar vertebrae are short, broad, and flat, and 

 somewhat curved forward. They are expanded and rounded at the free ends. 

 The centra increase in length posteriorly, the last lumbar having the greatest length 

 of any vertebra in the column. The neural spines increase in length from the first 

 lumbar to the fourth, those on the remaining lumbars being subequal, but the spine 

 on the ninth himbar is a little longer than the others. Median inferior ridges occur 

 on all the lumbars and are strongest at the middle of the series. The height of the 

 centrum of the ninth lumbar is 63 mm., width 73, and length 116. The highest 

 neural spine is 233. 



As above mentioned, the first of the vertebrae counted among the lumbars 

 may be the last thoracic vertebra, but as there is no indication of an articular facet 

 at the end of the transverse process it is not so considered in this place. 



The lumbar vertebrae in M. bidens appears to be more nearly equal in length 

 than in the present species, but are not different otherwise. 



The spines of the caudal vertebrae decrease rapidly in height posteriorly, and 

 disappear after the tenth caudal. The transverse processes resemble those of the 

 lumbars, but are shorter. They are last distinguishable on the eighth caudal. The 

 transverse process of the seventh caudal is perforated by a vertical foramen. Similar 

 but much smaller foramina occur on the sides of the centra of the eighth and ninth 

 caudals. In these vertebrae the inferior ridges are also pierced by foramina. In the 

 fourth caudal a ridge appears on the side of the neural arch on a level with the top 

 of the centrum, and similar ridges are found on the succeeding vertebrae as far as 

 the ninth caudal. The last ten vertebrae are without processes or neural arches. 



Sir William Turner states that the caudals of M. hidens are without vertical 

 foramina, but the figure in Van Beneden and Gervais' Osteography (plate 22) shows 

 them in the same position as in M. europseus. The inferior ridges, however, appear 

 to be imperforate in the former species. 



RIBS. 



The first seven pairs of ribs have both tubercle and head. The first is nearly 

 as long as the second, and is very broad at the proximal end. In the seventh pair 

 the head is double, one facet of the rib articulating with the facet on the posterior 

 margin of the centrum of the sixth thoracic vertebra and the other with the short 

 transverse process on the side of the centrum of the seventh thoracic vertebra. The 

 eighth and ninth pairs of ribs articulate only with the transverse processes of the 

 eighth and ninth thoracic vertebrae, respectively. The ninth pair of ribs, as already 

 stated, is nearly or quite as long as the eighth, from which it seems probable that a 

 tenth short pair was present originally. There is, however, no trace of a facet for 

 the articulation of such a rib on the end of the transverse process of what appears 

 to be the first lumbar vertebra. 



The only dift'erence between the ribs of M. europxus and those of M. hidens 

 appears to be that the first pair is much longer proportionately in the former species. 



