380 Williston — New Family of Reptiles from the 



almost conclusively, that the New Mexico beds are the strati- 

 graphical equivalent of the lower or Wichita division of the 

 Texas beds. The presence of certain forms, like those of 

 Dimetrodon, either closely allied to or identical with Texas 

 species, indicates a faunistic relationship between the New 

 Mexico and Texas faunas. On the other hand, the majority of 

 the New Mexico genera, and perhaps all the species, will be 

 found to be distinct from those of Texas, indicating either 

 interrupted communication between the two not very widely 

 separated regions during these Permian times, or different 

 environmental conditions. The latter conclusion seems the 

 more probable one, since those forms most nearly allied' are 

 chiefly from the red clays and red sandstones quite like those 

 of the Texas deposits, while most of the unlike forms come 

 from sandstones or clays unlike anything in Texas. Further- 

 more, the entire absence of concretionary material, pebbly sand- 

 stones, and apparently of all fish remains, may also indicate 

 different environmental conditions. Remains of sharks and 

 dipnoans are rather abundant in Texas deposits, and while they 

 may not be absolutely characteristic of marine or brackish 

 waters, they probably are. Of interest is the fact that there 

 is not a single fragment in the New Mexico collections that is 

 even suggestive of Naosaurus. perhaps the most widely dis- 

 tributed, and at the same time fragmentary and tantalizing of 

 Texas fossils. 



A full discussion of the Yale collection of New Mexico 

 Permian fossils would be beyond the limits of a single maga- 

 zine article, and will be given elsewhere, with figures of some 

 of the more characteristic specimens and of Marsh's types. I 

 restrict myself here to a description of a remarkable new family 

 of reptiles, coming from the very base of the deposits in the 

 vicinity of El Cobre. 



Limnoscelid^e, family new. 



Limno8celis paludis, genus and species new. (Figs. 1-7.) 



The description of this genus and species is based upon two 

 specimens, both from the same immediate locality in Rio 

 Arriba County, New Mexico, and both enclosed in a like matrix, 

 a dark, rather fine-grained sandstone, in nodular form. These 

 two specimens seem to be specifically identical, as the slight 

 differences observed between them may well be due to age or 

 conditions of fossilization. Of one of them (No. 809), there 

 is a neai-ly complete skeleton save the skull and front feet, and 

 a part of one of the hind feet; the preserved parts lie, for the 

 most part, in orderly articulation. The second specimen 

 (No. 811) is almost perfect, the only missing parts that I 



