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University of California Publications in Geology L Vo1 - 10 



These jaw fragments now seem to me to be somewhat less enig- 

 matical, since Merriam has pointed out that they do not belong to an 

 Ichthyosaurian. In 1906 Merriam 9 described a reptile, widely dif- 

 ferent from the ichthyosaurians but with a still uncertain systematic 

 position, Omphalosaurus. It is found in the Middle Triassic of 

 Nevada, and is thus approximately in the same horizon as Pessopteryx. 

 The reproductions of the teeth of Omphalosaurus that are found 

 in this work did not suggest to me any thought of the enigmatical 

 teeth of Spitzbergen. Merriam, however, in 1911, 13 has shown 

 the great similarity between the Omphalosaurus teeth and the teeth 

 referred by me to Pessopteryx, and since Merriam and Bryant 14 the 

 same year prod viced new figures of Omphalosaurus teeth I can myself 



Fig. 5. — Phalanges from the Lower Saurian horizon on Spitzbergen, X % 

 (after Wiman). 



state the identity. But seeing that the teeth are identical, in what 

 relation do then Omphalosaurus and Pessopteryx stand to each other? 

 Of the former only parts of the cranium with teeth and biconcave, 

 iehthyosaur-like cervical vertebrae are known, and, again, of the latter 

 vertebrae, extremity and girdle bones are found. Therefore a com- 

 parison cannot be made. One can, however, think of two possibilities. 

 The one is, that all of the material represents Omphalosaurus. Mer- 

 riam seems to be inclined to this interpretation. One would then have 

 to imagine a reptile with a relatively short head and a body that in 

 detail had developed on the same line as Ichthyosaurus. Such a paral- 

 lelism is of course not inconceivable, but less probable. The other 

 probability is that an ichthyosaurian Pessopteryx is before us, but 

 that, together with its bones, jaw fragments of Omphalosaurus occur. 

 It is easily possible that these very jaw bones have constituted the most 

 lasting part of the skeleton. In favor of a foreign intermixture also 

 speaks the fact that together with the Pessopteryx bones occur very 



