NORTH AMERICA AND THEIR VERTEBRATE FAUNA. 131 



was evidently free from the neural spine during life. Very slight rugosities 

 on the lower side indicate a weak attachment to the spine. However, as this 

 plate occxirs in the Wichita, and Aspidosaurus has never been found below 

 the Clear Fork, it is very possible that it represents a distinct form. 



Trematops (fig. 19).— As suggested by Williston, Trematops must be a 

 close relative of Eryops, and there can be little doubt but that its habits were 

 similar. The head was proportionately larger, and shows some very different 

 structures, as the postorbital openings (closed otic notches), the elongate 

 nares, or nares united with preorbital openings and the median opening 

 between the premaxillaries. There can be little doubt that the anterior 

 median opening, and perhaps a part of the elongate openings which include 

 the nares, were the seat of glands of some sort, perhaps 

 connected with the lateral line system. What the use 

 of such glands could have been we can not conjecture, 

 but it is very possible that some sense was located in 

 them which we can not appreciate. In reading Dean's 

 account^ of the feeding habits of the Lung Fish, one is 

 impressed with the possibility that these lowly animals 

 may have had a totally different means of receiving 

 impressions from the external world than those which 

 we usually attribute to them. 



The body of Trematops was not unlike that oi Eryops. fig ig.-Restoration of the 



■J J^ -> c head of Trematops mtl- 



Williston believes that it had a short tail, such as is len wmiston. About 



1 1 1. 1 1 -1 • one-fifth natural size. 



common m heavy -bodied amphibians. 



Lysorophus (fig. 13). — -This rather widely spread genus, foimd in Texas, 

 Oklahoma, and Illinois, was a slender, snake-like perrenibranchiate. Willis- 

 ton has found minute limb bones in the nodular masses which inclose the 

 skeletons of Lysorophus, and is inclined to believe that they belong to that 

 genus. This is not improbable, but it must be remembered that there are 

 other forms found in the same places and in the same nodules, and the limb 

 bones may have belonged to any one of the genera, or all may have possessed 

 them. The skull of Lysorophus is slender, but not long; rather more like an 

 Amphisb^nian or a Csecilian than a snake. The vertebral colimm is long, 

 and is always found more or less perfectly coiled, a condition which led Bam- 

 to suggest that they might be embryos. This is hardly possible, because of 

 the well-ossified condition of the vertebrae and the skull, and is not accepted, 

 so far as I know, by any writer upon this animal. 



If the creature did have limbs, they were very small and practically use- 

 less. If not snake-like, it was shaped like Proteus or Amphiuma, and was 

 very probably similar to them in habits (WiUiston). The skeletons are 

 found in great numbers in very limited localities, suggesting the gathering 

 together of large numbers of individuals in slowly drying pools, which in 

 their slow contraction forced the creatures together in large numbers in the 



» Dean, Proc. Zool. Soc. London, 1906, p. 172. 



