xi. RHAMPHORHYNCHUS BUCKLANDI. 225 



O'4 in the smallest part. The proximal end is widened ,to 0*8 ; 

 the distal end measures 0*5. 



The third wing-finger joint (p m ) is of equal length, but only 0*25 

 inches in the narrowest part, widened proximally to 0-53, distally 

 to 0-4. 



The fourth phalanx (p) is a very slender bone, which from the 

 proximal end proceeds straight for about two-thirds of the length, 

 and then bends inward. The bone is like a long curved awl, 

 beginning with an articulating face 0-35 inch broad, from which 

 it contracts by a curve on the inner face, and then proceeds by 

 a continual tapering to a fine rounded termination. Length 6-5 

 inches. 



All the bones which have been mentioned are smooth and 

 polished on the surface ; they were all hollow in the parts having 

 any considerable diameter ; and in most cases they have yielded 

 to compression, so as to present longitudinal grooves, as well as 

 a very elliptical section. They were originally of a compressed 

 figure, the greatest diameter of the finger-bones being parallel to 

 the greatest width of the articulating faces. 



The substance of the bones is traversed lengthways by Haversian 



Diagram LXXV. Scale magnified 200 times. 



i. Lacunae in bony scale of lepidotus. 2. Lacunae in leg bone of alligator. 

 3. Lacunae in phalangal bone of Rhamphorhynchus Bucklandi. 



canals, and dotted everywhere with lacunae of various figures, with 

 many short excurrent somewhat branched tubules. This structure 

 can be paralleled in the bones of the alligator and other reptiles, 

 and is not always easy to be distinguished from- the corresponding 



