WINGED REPTILES. 



319 



its first and second bones there was a marvelously perfect pulley-like 

 joint, permitting the flexion of the finger through an arc of nearly one 

 hundred and eighty degrees. When not in use in support of the wing 

 membrane, the finger could have been folded back close to the arm, 

 touching each other nearly on the back. In fact these bones have been 

 found fossilized in this position. 



Attached to the whole length of the arm and finger to its curved 

 extremity, there was a thin, and certainly strong, membrane, which 

 continued on the sides of the body and legs, probably quite to the 

 rudimentary feet. Impressions of this membrane have been found, 

 showing every fold and crease, as though cast in plaster-of-paris. 



In size these highly specialized 

 pterodactyls reached, as outspread 

 in fiight, the enormous expanse of 

 more than nineteen feet from tip to 

 tip of fingers. The length of the 

 body from tip of bill to toes was 

 about eight feet of which the head 

 was nearly a half. Contemporane- 

 ous with these gigantic species were 

 many others of smaller size, while 

 related forms of an earlier period 

 scarcely exceeded the stature of a 

 common sparrow. 



The earlier pterodactyls were 

 smaller and in many other respects 

 much less specialized than the latter 

 ones, that is they departed less 

 widely from the true reptilian type. 

 Of these perhaps the best known 

 is the Ehamphorhynchus, a res- 

 toration of which is given herewith, based upon a nearly com- 

 plete skeleton in the Yale Museum, a specimen of great interest, 

 because it shows so clearly the impressions of the wing membrane, 

 wholly without hair, feathers or scales. In this pterodactyl, the jaws 

 were provided with long and sharp teeth, the neck was less stout, 

 the shoulders were loosely articulated, the bones of the wings less 

 elongated, the legs stouter. Furthermore, it had a long, slender 

 and flexible tail, provided at its extremity with a diamond- 

 shaped membranous expansion, which doubtless served as a steering 

 organ or rudder in flight. Between the Ehamphorhynchus and Ptera- 

 nodon there were many intermediate forms, both large and small, with 

 and without teeth. Species of Ornithocheirus, nearly as large as those 

 of Pteranodon, which they closely resembled, except in the presence 



H 



\ 



Anterior Extremity of Wing of Ptera- 

 nodon, Nine Feet in Length. 



