academy op scENCEs] PUBLISHED RESULTS. 127 



and Proteus, but thinks it very probable that it was close of kin to the ancestors of these forms 

 (see table facing p. 133). This same paper discusses salamander-like footprints from the Texas 

 red beds and newly discovered ventral ribs in Labidosaurus. 



Another article, entitled " The Cotylosauria," 84 is very largely a redescription of Labidosau- 

 rus incisivus from a specimen in the University of Chicago collection originally described by Case. 

 Williston also discusses the history of the origin and use of the term Cotylosauria and adds a 

 protest against the later work done on the taxonomy of the reptiles, as follows (p. 148) : 



In a recent review of the literature of the Reptilia, I find all of the older groups usually called orders have been 

 raised in recent years by well-known writers to superordinal or subclass rank, save the I chthyosauria and Chelonia, 

 the two groups of all others most entitled to high rank! And most of the suborders have been elevated to orders — 

 thirty or more. And what has been gained? 



Williston's third paper on these ancient forms, published in 190S, is on " ' The Oldest Known 

 Reptile ' — Isodectes punctulatus Cope." 85 This species, which is from the Coal Measures of Linton, 

 Jefferson County, Ohio, was unhesitatingly referred by Cope to the Reptilia and said by him to 

 be " the first identification of a true reptile in the Coal Measures." However, because of recent 

 studies connecting the Stegocephalia so intimately with the Reptilia, it is somewhat hazardous 

 to affirm positively that the specimen, which lacks the skull with its distinctive parasphenoid 

 bone, is a true reptile. Nevertheless, Williston does not see in the skeleton a single character 

 which is not reptilian. M. Thevenin, of France, had recently described an air-breather from 

 the uppermost Carboniferous of France under the name Sauravus costei. This the distinguished 

 author believed to be rhynchocephalian, but Williston does not consider it either a stegocephalian 

 or cotylosaurian type, as in the American forms the final proof would lie in the degree of reduc- 

 tion of the parasphenoid bone, whether or not the condyles were paired. He further states that 

 from the evidence here shown it is clear that the primitive reptilian phalangeal formula was 

 that now persistent in the Lacertilia and Sphenodon, 2, 3, 4, 5, 4, the number 2, 3, 3, 3, 3, so 

 characteristic of the mammals, being a late specialization and having no genetic relationship 

 with the similar formula of most turtles. In other words, the phalangeal formula is not of the 

 great importance that some authors attach to it. 



Finally, Williston says (p. 400) : 



There are those who believe that the reptiles arose from two distinct groups of the Amphibia, one from the ilicro- 

 sauria, the other from the Temnospondyli, and I must confess that Isodectes helps that theory materially, for its relation- 

 ships with the Microsauria on the one side can not be gainsaid. But, the close relationships between such forms as 

 Pariotichus, Procolophon, Telerpeton, the Pelycosauria. the Cotylosauria, Pareiasauria, and Temnospondyli complicate 

 matters here exceedingly, and leave the whole subject still in great obscurity. 



In the table of 1917 (facing p. 133), Williston derives the Amphibia and Reptilia as a whole 

 from the Protopoda, known only from their footprints in Devonian and Mississippian rocks. 



The year 1909 90 brought forth one of the most important of Williston's papers, "TheFaunal 

 Relations of the early Vertebrates," short but very fundamental, and a basis for much which 

 was to come. Here he compares in some detail the successive land faunas of North America 

 with those known elsewhere from Mississippian time through the Mesozoic, and gives a graphic 

 table showing the distribution, both in space and in time, of the principal groups above the 

 fishes. He summarizes his evidence as follows (p. 399) : 



The Pennsylvanian fauna has nothing distinctive, at least till near the close; there must have been a continuous 

 and free interchange of land animals with the eastern continent till near the close. Before its close, it had already 

 diverged and certain true reptiles had appeared. Before the beginning of Permian times an interruption of migration 

 occurred, producing a complete and continuous isolation of the Permian American fauna. With the close of these 

 times a long interval elapsed, during which physical conditions were almost uniform over a large part of the Rocky 

 Mountain area at least, during which interval we have no records of land or fresh-water life, but which is represented 

 in part by marine forms of remarkable character, possibly in part derived from American ancestors. With the reap- 

 pearance of land forms in the Upper Triassic we find certain evidence of free migrations again, with the closest relation- 

 ships between eastern and western forms, none of which could have been derived, immediately at least, from the 

 known American Permian types. The marine vertebrates of the Upper Jurassic, the next American air-breathera 

 of which we have any knowledge, indicate an advance in specialization over the contemporary forms from the eastern 

 continent, but they also indicate a continued migration of the aquatic forms at least. With the land forms again 



