178 



internal longitudinal ridge is very prominent, and extends from the proximal 

 angle to the distal articular face in line with the plane of the short acuminate 

 hook. The great ala is narrow, and rather stout ; tlie proximal articular face 

 slopes steeply outward. The stapedial pit is a narrow, straight groove (per- 

 haps partly closed by pressure). The knob is represented by a longitudinal 

 crest, bordering the meatus below on the outer side, and not continuing to 

 the distal articulation. The surface of the latter is crescentic, with an angle 

 on the outer anterior bolder. This angle is the summit of a short, low, rugose 

 ridge, which extends j)art way to the knob. Outer edge only of the great 

 ala radiate-grooved ; posterior angle of distal condyle produced. 



The dorsal vertebra is somewhat flattened by pressure; but the ball was 

 evidently transversely-cordate in outline. The bases of tlie diapophyses are 

 very rugose : an angle from the articular cartilage is directed toward it from 

 tlie rim of the cup. Inferior face with an obtuse median keel. The odontoid 

 hone is deeper than long (fore and aft). 



As compared with L. micromus, this species differs in the much less 

 attenuated premaxillary and maxillary bones, the anterior nostril, and absence 

 of facets on the crowns of the teeth; from L. proriger in the absence 

 of narrow concave facets on the anterior teeth, and anterior position of the 

 nostril ; from L. dyspelor in the less compressed, or less knife-shaped, dental 

 crowns, and totally different form of the condyle of the quadrate. 



Measurements. 



M. 



Leugth of tUc bases of the two i)reuiaxillary teeth 0.026 



Width of the bases of the two premaxillary teeth 0.034 



Length of the bases of the two maxillaiy teeth 0.042 



Depth of the anterior suture of the maxillary 0. 028 



Depth of the maxillary at the end of the uarcs 0.038 



Length of the quadrate 0.082 



Length of the distal condyle 0.040 



Width of the distal condyle 0.017 



Width of the great ala on the inner side 0. 032 



Width of the inner face above the meatus 0. 0.!7 



Length of the hook from the stapedial pit 0.028 



Length of a dorsal vertebra 0. 009 



Diameter of the ball, vertical ., ^.^~j 



Diameter of the ball, transverse 0.048 



This species was discovered by Prof. B. F. Mudge, who dug the type- 

 speciineii from the gray shale of tlie Niohrara Cretaceous, half a mile soutli 

 of the Solomon River, Kansas. 



