REPTILIA : SPECIES INCERTAE SEDIS 137 



are two or three small intercentra in the collection of suitable 

 size for this arch. Notwithstanding these facts, such an elongate 

 curved spine for an amphibian would be most extraordinary and 

 unheard of and the absolute identity of the lateral markings in 

 this and the flat spines renders it almost certain that they all pertain 

 to one species of reptile. 



Associated with these spines are a lot of surface fragments of 

 similar spines. They all agree in having inosculating ridges and 

 irregular bosses. Some are thicker and stouter, like those described 

 by Case for the base of his spine, having their diameters nearly 

 equal; others are quite thin, but they all agree in their characters. 

 Among them are two fragments having the lower end of the lateral 

 excavated surface with a short interval of rounded smooth spine, 

 and then on each side a very irregular large nodosity, the spine 

 again contracting below them. 



If there are two different forms of animals represented by these 

 various specimens, then evidently one is the Ctenosaurus rugosus 

 of Case; the other, Zatrachys apicalis of Cope. But I believe that 

 they all pertain to one form, which may be Cope's Z. apicalis. 



Certain it is that the creature or creatures possessing these most 

 peculiar spine structures will be found to be among the most remark- 

 able of vertebrates. 



SPECIES INCERTAE SEDIS 



Numerous limb bones, as well as vertebrae, from the Craddock 

 bone-bed are indeterminable. Not only because of their intimate 

 faunistic association, but because of their perfect preservation 

 and unique types I give figures and brief descriptions of some of 

 the more important ones. Some are undoubtedly new to science, 

 but nothing will be gained by giving them names. To facilitate 

 reference to them, however, I have designated them by arbitrary 

 signs, consecutive letters with the number 104, the lot number 

 under which they are registered in the University catalogue. I have 

 figured some of the smaller forms only; later studies of the ver- 

 tebrae and girdles may indicate by elimination the relationships of 

 some of the forms. It is very probable that most of the specimens 

 here described belong among the zygocrotaphic reptiles. 



