.1 ni.xos.iL'n Ml MM) 11 



tuiT, liiit with (Icrinal tulxTclcs of rcl;iti\cly siikiII size, wliicli Narit-d in 

 sliajH' and airaiiuciiiciit in (lilVcrciit species, and that not inii)n)hal)ly asso- 

 ciated with this \arie(l epidermal pattern there was a \aried color |)attern. 

 The theory of a color jiattei'n is hased chielK iinofi the fact that the larj^er 

 tul)t'rcles concentrate and heconie more mnnerous on all th(»se poiiions of 

 the liody exposed to the snn, that is, on the outer sm'faces of the fore an<l 

 hind hmhs, and appear to increase also aloiii;' the sides of the l)od\ and to 

 l>c more concentrated on the hack. On the less ("Xposed areas, the under 

 side of the hody and the inner sides of the limhs, the >maller tuhercles are 

 more mnnerous, the larger tul)ercles hi'ing reduced to small, ii-regtdarly 

 arranged patches. From analogy witii existing li/ards and snakes we ma\- 

 sui)])ose. thercfori', that the trachodons presented a darker appearance when 

 .seen from the hack and a lighter appearance when seen from the front. 



The thin cliaracter of the epidermis as revealed hy this specimen faxors 

 also the theory tliat these animals spent a large part of their time in the 

 water, which theory is strengthened by the fact that the dimimiti\e fore limh 

 terminates not in claws or hoofs, hut in a i)road extension of the skin, 

 reaching heyond the hngers and forming a kind of paddle. This marginal 

 wcl). which cotmects all the fingers with eaeli other, together with the fact 

 that the lower side of the fore limh is as delicate in its epidermal structiu'e 

 as the u])per, certainly tends to support the theory of the swimming rather 

 than the walking or terrestrial function of this fore paddle, as indicated in 

 the accoinj)anying i)reliminary restoration that was made l)y Charles R. 

 Knight working mider the writer's direction. One is drawn in the con- 

 ventional bipedal, or standing posture, while the other is in a (|uadrupedal 

 pose, or walking {)osition, sustaining or balancing the fore part of the body 

 on a muddy surface with its fore feet. In the distant water a large nmnber 

 of the animals are disporting themselves. 



The designation of these animals as the " duck-bilh'd " dinosam-s in 

 reference to the l)roa<lening of the beak, has long been considered in con- 

 nection with the theory of acjuatic habitat. The coinersion of the fore 

 limb into a sort of paddle, as evidenced by the Sternberg specimen, 

 strengthens this theory. 



This truly wonderful specimen, therefore, nearly doubles oiu' j)revious 

 insight into the hal)its and life of a \ery remarkai)le grouj) of reptiles. 



