File:Bulletin - United States National Museum (1969) (20478858096).jpg

Title: Bulletin - United States National Museum
Identifier: bulletinunited2471969unit (find matches)
Year: 1877 (1870s)
Authors: United States National Museum; Smithsonian Institution; United States. Dept. of the Interior
Subjects: Science
Publisher: Washington : Smithsonian Institution Press, (etc. ); for sale by the Supt. of Docs. , U. S. Govt Print. Off.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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A NEW WHALEBONE WHALE 33
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Figure 19.—^Lateral views of ankylosed lumbar vertebrae, USNM 11976, of Pelocetus calvertensis: a, sixth lumbar; b, seventh lumbar; c, eighth lumbar; d, ninth lumbar; e, tenth lumbar. height toward the hinder end of the series and are not uni- form in width. The minimum anteroposterior diameter (110 mm.) of the neural spine of the tenth lumbar exceeds the corresponding measurement (95 mm.) of the sixth lum- bar. Variable profiles are displayed when the neural spines are viewed from the side, the terminal end being rounded on the sixth and obliquely truncated on the ninth. The metapophyses of the sixth lumbar are longer, broader and thicker than on the succeeding vertebrae, those of the tenth being rather slender. The backwardly projecting dorsal portion of the neural arch on these lumbars does not extend far enough beyond the level of the posterior end of the centrum to be tightly embraced by the metapophyses of the next vertebra, except in the case of the seventh which is thrust back against the base of the eighth's neural spine and fused with it for a depth of 60 mm. Toward the hinder end of this series of consecutive lumbars the metapophyses tend to approximate their opposites more closely and their anterior ends become slightly more elevated. On all five lumbars the metapophyses project forward beyond the level of the anterior end of the centrum. An increase in the anteroposterior diameter of the cen- trum is observable from the sixth (120 mm.) to the tenth (137 mm.) as well as the width. The neural canal is progressively reduced in width to 26 mm. on the tenth lumbar. The median longitudinal ridge on the floor of the neural canal is markedly reduced on the tenth lumbar. The pedicles (neurapophyses) of the neural arch are all compressed from side to side, but vary in minimum anteroposterior diameter from 78 mm. (sixth lumbar) to 70 mm. (eighth lumbar). From the anterior to the posterior end of this series of five lumbars the broad and rather thin transverse processes decrease in length as well as in breadth on the distal half, but very slightly in relative position and direction. The distance between the ends of opposite transverse processes decreases from more than 420 mm. (sixth lumbar) to 365 mm. (tenth lumbar). As mentioned previously this whale was a mature indi- vidual which displayed a far advanced stage of osteophy- tosis. A continuous thick irregular osseous band extends the entire length of the ventral aspect of these five consecu-

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