MORPHOLOGICAL REVISION 



111 



face of the proximal end which is continued as a deep groove on to the proximal 

 articular surface. The shaft is curved slightly outwardly and much more antero- 

 posteriorly. The distal end is divided between short horizontal face and a larger 

 one inclined upward and inward; both of these articulate with the astragalus. 



The fibula is slightly expanded at the proximal end with a concave facet on the 

 posterior surface, into which fits the head of the tibia. The shaft is slender, the 

 distal end expanded and thin with three facets. 



The tarsus has eight bones. The astragalus resembles, to some extent, the 

 same bone in the Pelycosauria; there are prominent articular faces on the distal end 



Fig. \o. — Reconstruction of Labidosauru*. After Broili. About \ natural size. 



and the outer side of the distal portion. On the inner side, the astragalus is closely 

 united to, or fused with, a small centrale. Above, the astragalus and calcaneum 

 are in close contact, but there is a distinct foramen between them. The calcaneum 

 is flat and thin and roughly round in outline. There are five distal elements. 



The number of phalanges is uncertain, but it seems probable that the primi- 

 tive number 2, 3, 4, 5, 3-4 was present. The phalanges were fairly long and heavy, 

 indicating that the animal had a large, well-formed foot. 



Measurements. 



No. 641 University of Chicago: mm 



Greatest length of interclavicle . 77 



Greatest breadth of the head of the inter- 

 clavicle, 23.5 



Anteroposterior length of scapula-coracoid 52.5 



Breadth of same at humeral cotylus . . 36 



Length of the head on median line from 

 posterior edge to a point opposite 



middle of nares 120.5 



Interorbital width 26 



Breadth of skull at posterior end . 127 



Breadth across orbits 80 



Breadth across nares (approximate) . . 30 



Length of lower jaw 150 



. . 66 



Greatest length of humerus 



Breadth of lower end of humerus 30 



Breadth of lower end of femur . . 26.5 

 Specimen described by Broili: 



Total length of skull in the middle line . 185 



Breadth of skull near posterior end . 165 



Breadth of skull at posterior end of orbits, 13 



Breadth of skull at anterior end of orbits, 7 



Breadth of skull at end of snout. . . 2 



Length of anterior nares 18 



Breadth of anterior nares I 



Specimen described by Broili — Continued. mm 

 Distance between nares .... 21 

 Distance posterior border of nares to ante- 

 rior border of orbits 51 



Length of the orbits 4 



Breadth of the orbits 3 



Distance between the orbits . ... 27 



Distance of orbits from edge of skull . . 7 

 Height of the skull above foramen magnum 8 



No. 4883 American Museum: 



Length of femur 70 



Width lower end of femur 35 



Length of tibia 49 



Length of fibula 56 



No. 4876 American Museum: 



Length of tibia 43.5 



Length of fibula 50.5 



Length of tarsus and foot as laid out . 83 



No. 4394 American Museum: 



Length of interclavicle 107 



Breadth of anterior end of interclavicle 55 



Length of scapula 106.5 



Greatest diameter of cotylus .... 50 



