HEPTILIA AND AMPHIBIA 203 



Though the work of the last few years has been inimical to our most 

 cherished theory, we can point to some positive results. Our knowledge 

 of the osteology of the Paleozoic amphibians and reptiles has been enor- 

 mously increased; we ate coming to a realization of the great abundance 

 and variety of life in the early periods ; the habits, distribution, and rela- 

 tionships are all coming to be better understood, and we can soon hope 

 to have a basis for enduring hypotheses of development. Even now we 

 know that the connecting link between the amphibians and reptiles is well 

 understood. Broili believed that Seyniouria was an amphibian until he 

 saw the palate ; Lijsorophus is called both amphibian and reptile because 

 the condition of the occipital condyle is in dispute ; Trematops and 

 Cacops have vestigial parasphenoids. But these are all highly specialized 

 forms ; when we find a small, generalized amphibian in which we can not 

 determine whether the occipital condyle is single or double and in which 

 the parasphenoid is in doubt, we can say that the gap is closed. 



Broom and Williston have lately made the suggestion that the relation- 

 ship between the Pelycosauria of Xorth America and the Therapsida of 

 South Africa is so close that it may be well to revive Cope's old order of . 

 Theromorpha to include them; this is, however, a tentative suggestion 

 based on a community of very primitive characters. 



And now as to future work. ^lore material, carefully collected, with 

 notes of the exact horizons; a careful study of the beds, to determine as 

 far as possible the conditions under which the animals developed and the 

 factors which controlled their evolution ; finally, an effort to make out 

 the lines of migrations. The problems are broader than pure morphology. 

 The highly specialized amphibians and reptiles must have lived under 

 very restricted conditions, and as we find the Pelycosaurs, for instance, 

 from Texas across the United States and into Prince Edward Island, and 

 even as far as Bohemia, we may go far toward restoring the condition of 

 large areas when we have a good idea of their habits. The true age of 

 the so-called Permian deposits will also be settled by a closer knowledge. 

 It has been shown that there are no vertebrates in the Texas beds which 

 will prove their Permian age. The fossils from the vicinity of Pitts- 

 burgh, discovered several years ago by Raymond, are certainly from the 

 Pennsylvanian. Last summer a specimen of Spirifer rochjmojitanus was 

 discovered either in or close above beds carrying Permian ( ?) vertebrates 

 in El Cobre Canyon, in Xew Mexico. It is evident that the position of 

 these vertebrates and amphibians of the end of the Paleozoic has been 

 placed rather higher than there is warrant. Their exact position is yet 

 to be fixed. 



XV— Bull. Geol. Soc. Am., Vol. 23, 1911 



