394 



THE AMERICAN NATURALIST [Vol.LII 



by whose courtesy a photograph has been used for com- 

 parison. Renault has described a great variety of bac- 

 teria, many of which are apparently similar to the bacteria 

 of to-day. 



In searching for evidences of disease among fossil 

 vertebrates I have been interested in making the above 

 comparisons. In the light of the above study it seems 

 probable that some of the instances of opisthotonos and 

 pleurothotonos among fossil vertebrates may be due to 

 acute cerebrospinal infections, the petrified skeletons 

 exhibiting trismus, rigidity of the limbs, and the peculiar 

 backward curvature of the vertebral column so common 

 to-day as clinical manifestations of spastic distress. This 

 is especially probable in the cases where the skeletons 

 exhibit such marked opisthotonos and pleurothotonos as 

 do many of the specimens' above referred to. It may 

 then be said that opisthotonos as seen in the skeletons of 

 fossil vertebrates indicates disease only in those exag- 

 gerated cases of spastic distress as is evidenced by the 

 attitudes assumed by fossil vertebrates, such as the small 

 dinosaur, Struthlontimns alius, and the bird, Archaop- 

 teryx macroura. Not all vertebrates preserved in opis- 

 thotonus were victims of disease, but many of them sug- 

 gest a strong neuro-toxic condition. 



