508 



RICHARD SWANN LULL ON 



impressions both of the tail and of the ischial callosity of the same indi%ddual may be 

 seen, the difference in the two marks being such that they could not have been made 

 by the same organ, the former being a narrow groove while the latter is a broad rounded 

 depression. 



The type specimens are nos. | and i, of the Hitchcock cabinet, from Turner's Falls, 

 Massachusetts. 



Genus Apatichnus E. Hitchcock. (Deceptive track.) 

 AjKiticJutus E. Hitchcock, '58, p. 99. 



Generic characters. Bipedal in gait, digitigrade, functionally tridactyl. Claws on 

 the pes are acuminate and the proximal pad of digit IV is very small. There is a caudal 

 trace. 



The distinction between this genus and Anomoepus was supposed to be the presence 

 of a hallux in the present group and its absence in the other. It has been found in both 

 genera thus removing several of the species from Apatichnus to Anomoepus as they were 

 clearly of the latter type but were known to possess the hallux. 



Apatichnus, of which .4. circumage?is is the type, differs from Anomoepus in the 

 much shorter hallux and in the fact that, while the divarication between digits II and 

 III is less, that between III and IV is much greater, giving to the middle digit the 



appearance of being exserted far beyond the 

 others, a point which is well brought out in 

 the figures. 





•\//A 



Apatichnus circumagens E. Hitchcock. 



Apatichnus circumagens E. Hitchcock, '58, 

 p. 100, pi. 17, fig. 5; pi. 35, fig. 6. 



Specific characters. Pes: divarication of 

 digits I and II, 53°; of II and III, 18°; of III 

 and IV, 46°; of I and IV, 116°. Length of 

 digit I, .025 m. ; of II, .035 m. ; of III, .062 m. ; 

 of IV, .053 m. Length of foot, .075 m. These 

 measurements are taken from no. ^, the fig- 

 itred specimen; those of Hitchcock, from no. 

 ^, are somewhat larger and the- angle of 

 divarication of digits II and III is greater. 



Hitchcock gives the length of the entire foot and heel as .127 m., the foot alone being 



half that length. The average length of step is .240 m. 



1 

 1 



Fig. 29. Apatichnus circumagens E. Hitchcock. 

 Impression of right pes. X }. From no. V, of the 

 Hitchcock cabinet. 



