Ormthichnology* 317 



O- di versus. 



a clarus. 



^ platydactylus. 



« O tetradactylus. 



O palmatus. 



O minimus. 



Specific Descriptions, 



O. giganteus. Toes three ; length of the foot, fifteen inches, 

 exclusive of the claws. In one specimen, the claw is at least two 

 inches long, and even then a part of it appears to he missing : in 

 general it is not more than one inch, but seems to be broken off. 

 The whole length of the foot, consequently, is sixteen or seventeen 

 inches! Length of the successive steps, between four and six feet! 

 toes somewhat tuberculated ; the inner one, in some specimens, dis- 

 tinctly exhibiting two protuberances, and the middle one three, al- 

 though less obviously. Average thickness of the toes, one inch and 

 one fourth ; breadth of do. two inches. Occurring only at the quar- 

 ry in Northampton, on the east side of Mount Tom, where it is 

 abundant. I found in one spot, six tracks of this species in succes- 

 sion, the average distance between them, being four feet. This case 

 is represented in Fig. 1, along with three other tracks of the same 

 size, and one of smaller size, on the same rock. Indeed, I suspect 

 from the numerous examples which I have seen of tracks at the 

 distance of four feet, that this was the ordinary step of the bird 

 when walking ; while it w^as able to lengthen it to six feet, when 

 moving rapidly. The examples where the steps are six feet, are 



not common. , 



In one part of the quarry above referred to, I found the steps of 

 four individuals of this species, all pointing in the same direction, and 

 nearly parallel to one another ; showing that four birds must have 

 moved alono- nearly together ; and rendering it probable, that this 

 species was°gregarious. The distance between the several rows of 

 tracks, is four or five feet. An attempt is made in Fig. 21, to rep- 

 resent the O. giganteus of the natural size, as it extends out m 

 bold relief, on a specimen in my possession. The claws are brok- 

 en ofF. It is the under side of the foot, that is shown m the figure. 



Incredible almost as this description may seem, the specimens 

 which I have obtained of this enormous species, are nevertheless 

 more satisfactory, perhaps, than of any other species. The whole 



