VERTEBRATE PALEONTOLOGY IN 191 1 577 



which the name Limnoscelis paludis is suggested, was evidently 

 aquatic or subaquatic in habits — as is indicated by the 

 extremely imperfect ossification or even wholly cartilaginous 

 condition of the wrist and ankle joints— and had the whole of 

 the lower surface of the body protected by a bony panoply. 

 Its nearest relationships are evidently with the contemporary 

 genus Diadectes, which is one of the best-known representatives 

 of the cotylosaurian order. Among the distinctive differences 

 from that genus are the longer and smoother skull, with its 

 parietal foramen of inferior calibre, the absence of expansion 

 in the ribs, which appear to be single-headed throughout and 

 the aforesaid slight ossification of the wrist and ankle. The 

 teeth, moreover, are of a conical and prehensile type. In the 

 opinion of the author, it seems probable that the American 

 Diadectes and Limnoscelis will eventually have to be classed 

 with the Old World Pariasaurus and its near relative Pro- 

 pappus. 



The whole subject of American Permian vertebrates is more 

 fully elaborated by the same writer in a volume published under 

 that title by the University of Chicago. In this work Prof. 

 Williston reviews all the known representatives of the Amphibia 

 and Reptilia included in this fauna. The reptiles he divides 

 into (1) Cotylosauria, with the families Diadectidce, Limnoscelidce, 

 Seyniouriidce, and Pariotichidce, and (2) Theromorpha, which 

 include the Sphenceodontidce (Clepsydrops), Poliosauridce and 

 Caseidce. The inclusion of these families among the Theromorpha 

 or mammal-like reptiles is a wide departure from the classifica- 

 tion adopted by many palaeontologists, some of whom place 

 Clepsydrops and its relative Naosaurus in the Rhynchocephalia. 



To a great extent the classification adopted by Prof. £. C. 

 Case in the quarto volume published by the Carnegie Institution 

 of Washington under the title of A Revision of the Cotylosauria 

 of North America agrees with that followed by Prof. Willis- 

 ton ; the Pariotichida?, Pariasauridm and the Procolophonidce, 

 which many authorities class in the mammal-like group, being 

 included in the Cotylosauria. That ordinal group is taken, in 

 fact, to comprise all those primitive reptiles in which the 

 temporal region of the skull is roofed with bone, the ribs single- 

 headed and the neural arches of the vertebrae low and broad, 

 with short spines and swollen sides. The order, which is less 

 primitive than at first supposed, although more primitive than 



