1887.] ^^^ [Cope. 



The confluent extremities of the ischium form a surface of contact with 

 the eartli on which the animal probably rested at times, as I have sus- 

 pected to be the case with the genus Megadactylus.* The pubes are 

 directed downwards, and being longer than the femora have projected 

 below the knees. It is probable that the animal rested on the apices of 

 these bones also, as suspected by Marsh in the case of the Goniopoda of 

 the Jurassic. 



The/emw is remarkable for the incurvature of the proximal extremity, 

 so that it might be said to have a neck, but that there is no great tro- 

 chanter. This form is necessary to avoid contact witli the large pubic 

 region. The shaft is a slightly flattened cylinder at the middle, and is 

 a little flatter below. Rotular groove slight. Internal condyle narrower 

 than external, and produced a little farther posteriorly. 



M. 



Length of femur 215 



-r^. . <• J 1 r anteroposterior 024 



Diameters of condyles \ ' 



( transverse 030 



Diameters of shaft at middle j anteroposterior 014 



( transverse 016 



Neither bones of the lower leg nor of the tarsus are certainly preserved. 

 A phalange is of considerable size, and indicates perhaps the first of the 

 internal digit, which is especially large in Megadactylus. The trochlear 

 surfaces are well marked and smooth, the proximal simple, the distal 

 hour-glass-shaped, and with well-marked lateral ligamentous fossae. The 

 two ligamentous insertions of the proximal extremity are well developed 

 and of unequal size. 



M. 

 Total length 043 



„. , . , fveitical 018 



Diameters, proxunal \ ^ ^_^ 



(.transverse 015 



Diameters, distal f P^«^™^1 013 



( transverse 013 



An ungual 2^hnlan(je is remarkable for its abrupt but regular curvature, 

 and its great compression. The superior edge is the arc of a circle whose 

 center is on the inferior edge just in front of the ligamentous insertions. 

 The latter form a ridge of each side, just in front of the articular face, 

 and are separated by a deep fossa. The insertion of the extensor liga- 

 ment is a concave triangular space above the articular surface. The apex 

 is lost. 



Vertical depth of unguis 018 



Width do. at base of articular face 010 



This unguis is so proportioned as to have fit the penultimate phalange 



* Trausac. Amer. Philos. Soc, 18G9, Plate xiii. 



PROC. AMER. PHILOS. SOC. XXIV. 126. 2c. PRINTED OCT. 20, 1887. 



