No. 4. — The fossil cetacean, Dorudon serratus Gibbes. 



By Frederick W. True. 



Some months ago the authorities of the Museum of Comparative 

 Zoology very generously placed in my hands for study the type speci- 

 mens of the fossil cetacean, Dorudon serratus, which was originally de- 

 scribed by Dr. R. W. Gibbes in 1845. The material was without any other 

 label than the following : — " This entire lot belongs to the R. W. Gibbes 

 collection, marked * Eocene ' (no locality), but probably South Carolina." 

 A glance at the specimens, however, satisfied me that they included the 

 types of Dorudon serratus, and this was confirmed by reference to the 

 original description and figures in the Proceedings of the Academy of 

 Natural Sciences of Philadelphia, 1845, Vol. 2, page 254-256, Plate 1. 



The type specimens themselves consist of (a) a fragment of the right 

 maxilla, containing three molar teeth nearly complete, (6) an upper 

 premolar with a fragment of the maxilla attached, in which is a second 

 alveolus, and (c) an incisor or canine tooth. These were figured, as 

 above mentioned, in 1845. Associated with the types by Gibbes, and 

 contained in the lot of material now at liand, are (d) the left half of a 

 mandible, nearly complete, but with the condyle missiug, some of the 

 teeth crushed and without crowns, and others lacking altogether ; and 

 (e) a small fragment from the right side of a mandible, to which is 

 attached a canine or incisor tooth with a broken crown. These speci- 

 mens were figured by Gibbes in a second article (Journal of the Academy 

 Natural Sciences of Philadelphia, 1847, series 2, Vol. 1, pages 1-15, 

 Plate 3, figures 1-2). 



In this latter article Gibbes figured (Plate 3, figures 5-6) also another 

 fragment which is in the collection, namely, (/) a portion of a left pre- 

 maxilla. He also mentioned (g) a fragment of a right premaxilla which 

 is present, and (h) figured (oj). cit., Plate 2, figure 1, two views, unnum- 

 bered) an incisor or canine tooth, which has likewise been preserved. 



In addition to the foregoing, the collection contains the following : — 

 (i) The zygomatic process of the left squamosal, incomplete ; (J) a 

 portion of the right parietal ; (F) the orbital plate of the right frontal, 



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