ART. 27 A FOSSIL PHYSETEROID CETACEAlv: KELLOGG 3 



ferring to a bituminous limestone [^bituminous dolomite as shown 

 by No. 11 in table of analyses, p. 45] from the Redrock Mountain,' 

 northeast of Lompoc, Santa Barbara Coimty, they report as follows : 

 "The last analysis (No. 11) represents limestone typical in lithologic 

 appearance of the limestone of the Monterey." The age of this 

 formation is probably Helvetian or later. 



Rostrum. — As the base of the rostrum and the braincase still re- 

 main in the sea cliff near Santa Barbara, an exact idea of this physe- 

 teroicl's relation to previously described skulls can not be given at 

 present. The general outlines of the skull, however, were probably 

 similar to Scaldicetus. According to the figures of Scaldicetus 

 viortezeleiisis given by Abel,* the extremity of the rostrum of that 

 species is not characterized by a lateral compression. This is the 

 most apparent difference between the rostrum of the Santa Barbara 

 cetacean (pi. 1) and that of Scaldicetus. The size of the teeth and 

 the general appearance of their dentinal axes indicate some relation- 

 ship with Ontocetus. All previously described skulls of fossil phys- 

 eteroids, in so far as can be judged from the imperfectly preserved 

 specimens now known, were characterized in part by the presence of 

 three teeth in the extremity of each premaxilla. In these forms the 

 extremity of the rostrum is formed by the premaxillae alone. In 

 this Santa Barbara skull, also, the premaxillae take part in the for- 

 mation of the extremity of the rostrum and three of the teeth on 

 each side are implanted in the premaxilla. The lateral compression 

 of the distal portion of the rostrum is quite noticeable in certain 

 genera, particularly so in Physodon patagonicus and Diaphorocetus 

 mediatlanticus. The extremity of the rostrum of this fossil phys- 

 eteroid was constricted from side to side and the inner margins of 

 the premaxillae are in contact along the median line as in Physodon 

 patagonicus, forming a roof for the mesorostral gutter. On com- 

 paring the dorsal view of this Santa Barbara rostrum with that of 

 Physeter^ other peculiarities become apparent. In the latter, the 

 rostrum is more or less attenuated anteriorly, but the abrupt con- 

 striction or lateral compression of the distal portion of the rostrum 

 has disappeared with the horizontal expansion of the rostrum. 



While removing the matrix it became evident that this skull had 

 partially decayed before it was completely buried in the sediments 

 which preserved it. Furthermore, some of the teeth were broken 

 off in the alveoli previous to its burial, for on removing the matrix 

 which covered the right mandible, the roots of the teeth were ex- 



3 Arnold,, R., and Anderson, R., Geology and Oil Resources of the Summerland Disti-ict, 

 Santa Barbara County, California. 



* Abel, O., Mem. Mus. roy. d'hist. nat. de Belgique, Bruxelles. vol. 8. p. 67, fig. 5 1905. 



5 Van Beneden, P. J., and Gervais, P., Ost(?irraphie des Cctac^s vivants et fossiles. 

 Paris, Atlas, pi. 19, figs. 5-6. 1880. 



