212 AN ATTEMPT TO DESCRIBE THE ANIMALS THAT MADE 



Appendix to Group IV. 



Remarks. — Some general resemblances between the foot of the 

 following genus and those of the preceding genera of this group 

 have led me to place it in an a])pendix, though very probably it 

 may prove to have very different affinities. 



Genus XI. TYPOPUS. 



Foot plantigrade, except the middle toe, which is strikingly digi- 

 tigrade ; trifid ; toes leptodactylous. Heel a prolongation back- 

 ward of the outer toe ; yet, from the anterior extremity of this, a 

 ridge extends nearly at right angles, which appears to form a basis 

 for the insertion of the other toes. 



Remarks. — If I had not very distinct tracks of this species, 

 I should not attempt to describe it, it is so anomalous and unlike 

 existing nature. The lateral character of the heel is one peculiar- 

 ity. But the ridge on the foot, running obliquely from this to the 

 roots of the inner toe, is more peculiar ; seeming, in fact, to be 

 only a curved continuation backward of that toe. I have been, 

 indeed, in doubt whether to consider it as a heel, or that and the 

 toe as one crooked toe. But the middle toe seems to have been 

 articulated to this ridge, though high up, leaving a cavity between. 

 Hence I have, upon the whole, regarded this ridge as a part of the 

 heel. That part of the heel which is a continuation backward 

 of the outer toe might be considered a hind toe, were not its 

 width and bluntness, as seen on the tracks, more characteristic of 

 a heel. 



Species 1. Typopus abnormis. (PI. X. Fig. 6.) 



Sauroidichnites abnormis, Am. Jour. Science, Vol. XLVII., Plate 

 3, figs. 6, 7, 8. 



