278 PROCEEDINGS OP THE ACADEMY OF 



In. 



Length on convexity, , 9f 



Chord from articulatory surface, 6f 



Surface slightly striated at the base on one side. 



No. 2. Penultimate. Proximally higher than broad, distally broader than 

 high ; two elevated articular surfaces proximally, distal condyles separated 

 by a deep groove and much prolonged inferiorly ; a fossa on each side ec- 

 centric to the condyle. Superior outline straight, inferior descending 

 behind. 



No. 3. Also penultimate, is flatter and more parallelogrammic .in section 

 than the last. 



No. 4. Antepenult? more cylindrical, condyles broken. 



In. 



Length, No. 2, , 4.75 



Proximal elevation, 1.75 



" breadth below, 1.75 



Breadth shank below, 1.25 



Distal width, 1.25 



" " of condyles below, 1.75 



No. 3, proximal breadth below, 2.125 



Breadth shank below, 1.50 



Terminal and inferior breadth distal condyles, 1.875 



No. 4. length, .6. 



Vertebrve. No cervical or dorsal vertebrae were preserved ; very few lum- 

 bars, a fragment of two of the connate sacrals and numerous caudals were 

 all as yet in Prof. C's possession. All are much constricted medially, or hour- 

 glass shaped, the centrum cylindrical in section throughout in most of the cau- 

 dals, the anterior of the latter and the lumbars of deeper vertical than trans- 

 verse diameter throughout. The articular surfaces were moderately shallow 

 biconcave in all, most strongly in the subproximal caudals. The neural arches 

 attached by permanent suture, and inferior surfaces for articulation of chev- 

 ron bones. None of the caudals offer indication of elevated neural spines ; 

 they appear to have been on the majority low, and of considerable longi- 

 tudinal extent. Articular surfaces for chevron bones cease near the middle 

 of series, so that we can safely infer that the tail was cylindrical. Zyga- 

 pophyses turned upward, not outward. 



In. 



Length of a median caudal, 4.625 



Breadth centrum, 2.375 



Length base neural spine, 3.25 



Length of a distal caudal (with neural canal), 2.875 



Diameter centrum transverse, Tl. 125 



" " vertical, 875 



Proximal caudal (with short diapophysis) length, 4.5 



Depth centrum, ' 3.125 



Width, " 3. 



Lumbar, depth centrum, 4.5 



The disproportion between the fore and hind limbs of the Iguanodon, 

 together with the compressed form of the tail suggested to Prof. Owen an 

 aquatic habit, a relation of proportions of limbs to habit seen in the tailless 

 Batrachia. The discovery of the massive short-toed foot of the Iguanodon 

 subsequently, has lent little countenance to the supposition of its entire adap- 

 tation to aquatic life. Dr. Leidy has regarded this disproportion in the cage 

 of the Hadrosaurus as an index of a habit like that of the Kangaroos (Macro- 

 pus, etc.), and that that monster rested in an oblique position on the hind 

 limbs and tail, and reached upwards with its muzzle and short fore limbs to 

 the foliage on which it fed. 



[Aug. 



