1922] Kellogg: Pinnipeds from Miocene and Pleistocene Deposits 95 



3. The ungual phalanges in Pinnipedia are uniissured, as in Adaptive Creodonts 

 and Fissipedia. In both groups of Inadaptive Creodonts the claws are fissured. 



4. The seals possess a tympanic bulla very similar to that of the Ursidae and 

 larger Mustclidae. In the Creodonta the tympanic is not usually expanded into 

 a bulla; in the later Mesonychidae a substantially similar bulla is present, and in 

 certain species of Eyaenodon a bulla of rather different type. In the Oxyaenidae, 

 as far as known, there is no tendency to form a tympanic bulla, and in the latest 

 survivor (Oxyacnodon) an incipient petrosal bulla takes its place. 



5. The united scapho-lunar of the Pinnipedia is a character which must have 

 preceded their aquatic adaptation, as in aquatic vertebrata generally the carpals 

 tend to become reduced and imperfectly ossified but not to become fused. In the 

 Inadaptive Creodonts there is little or no tendency to fusion of the scaphoid and 

 lunar ; the Adaptive Creodonts on the contrary early manifest a tendency in this 

 direction, and it has become complete and universal in the Fissipedia, and in the 

 Pinnipedia as well. 



6. In the form of the petrosal the Pinnipedia agree better with the Adaptive 

 Carnivora and Fissipedia than with any of the Inadaptive groups, and differ most 

 from the Oxyaenidae. 



7. There are a number of points of resemblance to the Ursidae and to a less 

 extent to the Arctoidea generally in the soft anatomy of the Pinnipedia. 



However, even this derivation is beset with several difficulties. The 

 following objections might be pointed out. 



1. The increase in size of the orbit due to enlargement of the visual organ for 

 sight under water would cause the orbit to encroach on the facial extension of 

 the lachrymal and in a comparatively short time it would be entirely within the 

 orbit. In other words the absence of the facial extension of the lachrymal may 

 be attributed to aquatic adaptation. 



2. An M2 is present in AUodcsmiis from the Temblor beds and it is also occa- 

 sionally present in Mirounga. An M 5 is sometimes present in Callotaria. The 

 evidence shows that the reduction of the true molars was very rapid in the 

 Otariidae, at least, whether due to the nature of the food or to unknown reasons. 

 In Eumctopias there is a wide separation between the surviving molar and the 

 premolar series. There might be some question as to what molar this one really is. 

 Eriqnathus has the upper molars widely separated from the premolars. The 

 molariform series as a whole are but slightly implanted, becoming defective early 

 by attrition and partly deciduous or abortive in old age. The disappearance or 

 reduction of teeth in the pinnipeds is very irregular. 



3. The statement that the seals possess a tympanic bulla very similar to that 

 of the Ursidae has been refuted by Van Kampen,i88 w ho has shown that the 

 bulla of both the Otariidae and the Phocidae is a composite one, formed of the 

 entotympanic and the annulus tympanicus or true tympanic as in the .ZEluroidea 

 or cats, though in external appearance it does resemble the arctoid type. 



4. The possession of a wholly consolidated scapho-lunar-centrale in the Pinni- 

 pedia may not preclude its derivation from a form which possesses these as separate 

 elements. Aquatic adaptation may or may not increase the separation of these 

 bones. The consolidation of the scaphoid, lunar, and centrale in the Sirenia 

 weakens Dr. Matthew 's argument here. 



5. The bears are of comparatively recent origin, being derived from the dog-line 



188 Van Kampen, P. N., Die Tympanalgegend des Saugetierschadals. Morphol. 

 Jahrb., vol. 34, pts. 3, 4, pp. 537, 542, 545. 1905. 



