346 Trof. 0. C. Marsh — Netv Cretaceous Pterodactyls. 



upward, as shown in Figures 1, 2, and 3. Seen from the side, the 

 jaws project forward like a huge pair of pointed shears. They are 

 very long, sharply pointed in front, and entirely destitute of teeth. 

 In no specimens examined, -young or old, have any indications of 

 teeth been detected. The margins of the jaws are smooth and thin, 

 as in many species of recent Birds. The jaws were probably 

 encased in a horny sheath. 



The bones of the skull are nearly all of extreme tenuity. With 

 the exception of the occipital condyle, and the lower ends of the 

 quadrates, all seem to have been pneumatic. 



Seen from above, the skull appears extremely narrow. A sharp 

 ridge extends from the end of the premaxillaries along the median 

 line to the true cranium, and is continued backward by the thin 

 elevated crest. The large antorbital openings thus seem near the 

 middle of the skull, and, as they are directly over the posterior 

 nares, they form part of the vertical apertures in the cranium, seen 

 in Figs. 2 and 3. 



The palate is deeply concave, and covered with bone, as far back 

 as the posterior nares. 



The bones of the skull are nearly all firmly ankylosed together, 

 and this makes it very difficult to determine the different elements. 



The premaxillaries are very large, and have coalesced with the 

 maxillaries. They appear to extend backward to the large antor- 

 bital vacuities. These apertures apparently include both the anterior 

 nares, and the lachry mo-nasal foss^, which are separate in most 

 recent birds. 



The orbit is of moderate size, and oval in outline, the apex being 

 below. There was apparently no ring of bony sclerotic plates, since 

 in the best-preserved specimens no traces of this have been found. 



The quadrate is firmly coossified with the other cranial bones, 

 and projects strongly forward. Its distal end is one of the most 

 characteristic parts of the skeleton. 



The sagittal crest is of enormous size, and serves to balance the 

 elongated jaws. It is very thin transversely, and during life was 

 probably more or less flexible. In form and direction, it resembles 

 the corresponding crest in the recent genus Basilicus. 



The occipital condyle is very small, and nearly hemispherical in 

 form. It is directed backward, and but slightly downward, thus 

 differing from this part in most of the members of the group. 



The Lower Jaws. — The lower jaws are very long, and quite 

 sharp in front, corresponding closely in this respect with the end of 

 the upper jaws. The rami are closely united by a symphysis which 

 extends from the apex to beyond the posterior extremity of the 

 dentary bone, as in the mandible of Bhynchops, and some other 

 birds. Behind the symphysis, the rami are comparatively slender. 

 The upper face is strongly concave. The articulation for the quad- 

 rate is deeply grooved obliquely, and the joint is a very strong one. 

 The front portion of this mandible during life was evidently pro- 

 tected by a horny covering, like that of the beak above. 



The nearly complete skull here described may be regarded as a 



