LYSOROPHUS, A PERMIAN URODELE. 



239 



some or all of these prints is due to real salamanders of modern 

 type. 



Ventral Ribs in Labidosaurus Incisivus. (Fig. 5.) 

 In a recent paper ' I stated my belief that ventral ribs would 

 eventually be found in some of the forms now classed in the 

 rather heterogenous group known as the Cotylosauria, and I sus- 

 pected that the specimen of Labidosaurus therein described pre- 

 sented such evidence, but could not be sure. This evidence has, 

 however, been made clear by further preparation of that speci- 

 men. In the removal of the matrix from the under side of the 

 pubes a small fenestra of accidental origin was found, and in this 





Fig. 5. Ventral ribs of Labidosaurtis incisivus, enlarged about two diameters. 



space, that is originally between the front end of the plate-like 

 pubes and the vertebrae, are seen abundant evidences of small 

 slender ribs, of some of which I give herewith a photographic 

 illustration. At this spot seven ribs are seen lying closely to- 

 gether and parallel, directed from the anterior outer corner of the 

 pubis inward and backward. Still further forward, and the con- 

 tinuation of these series, are further evidences of the same sort. 

 The ribs are much smaller than I had expected to find them, but it 

 is clear to me that the whole under side of the abdomen was en- 

 closed in a closely set armor of slender ossified ribs. This char- 



^ Journal of Geology, XVI., p. 148, 1908. 



