562 



THE AMERICAS' \ I TURA LIST [Vol.XLVI 



such fossils. 



The reader, at least this one, can not always determine the 

 exact size of the animals described; for example, that of 

 Seymonria baylorensis. On page 140 we are told that the figures 

 of the plates are of the natural size, unless otherwise stated, 

 wherefore we might conclude that the figure on Plate XXVI is of 

 the size of nature. However, on pages 51 and 52 the figures of 

 the same skull are explained as being one half the natural size, 

 and they are somewhat more than two thirds the size of the skull 

 of Plate XXVI. As the author seems not to state the size of 

 the animal we are left in doubt. 



The pn-M-nt writer would suggest that tin- important 



Plate V 



ought to have had its figures lettered so as to indicate what names 

 the author intended to apply to the various elements. By 

 digging in the text with sufficient assiduity the unfamiliar stu- 

 dent may, after struggling perhaps with such expressions as 

 "the real, so-called coracoid" (p. 57) and "the so-called true 

 coracoid" (pp. 97, 100), determine to what parts the various 

 terms are to be applied. 



Inasmuch as Dr. Williston argues that the exact content of the 

 terms Theromorpha and Pelycosauria and the exact relation- 

 ships of the groups can not yet be determined, it would appear 

 better to have retained Pelycosauria for the order which he calls 

 Theromorpha, especially since Case has employed Pelycosauria 

 in his monograph on the group. It is still more difficult to 

 follow Dr. Williston in displacing the well-founded family name 

 Clepsydropidae in favor of Sphenacodontida? ; when, according to 

 his own researches, the genus Sphenacodon, with great prob- 

 ability, does not belong in the same family as Clepsydrops 



Having uttered these mild complaints, it is a pleasure to 

 recognize the value of the services rendered to science by T>r. 

 Williston in his descriptions of Limnoscelis paludis, Seymouna 

 baylorensis, Varanosaurus brevirostris and Casea broilii. These 

 descriptions are based on materials so complete and so abundant 

 that practically the whole osteology of each is known. The re- 

 mains form a marked contrast with those on which Cope was 

 compelled to found most of his work on the Permian reptiles 

 and amphibians. 



