28 



Squamata — Mosasanrus. 



"Wall-case, 

 No. 7. 



The limbs are modified into paddles with no claws to the 

 terminal phalangeals and no foramen to the humerus. The 

 majority of forms were devoid of dermal scutes. 



Fig. 34.— Superior aspect of the oranium of Plotecarpus curtirostris (Cope) ; from the 

 Upper Cretaceous of N. America (greatly reduced), pmx, premaxilla; jhx, maxilla; 

 fr, frontal ; j;/-/, prefrontal (after Cope). 



Mosasau- 

 rus. 



Fig. 35. — Lateral and piotile views of a lower tooth of liodon, sp. 

 from the Upper Cretaceous of Maestricht, Holland, \. 



These great aquatic lizard-like reptiles, known as the 

 Mosasaurus, Liodon, etc., once inhabited the shoi'es of the sea in 

 which the uppermost Chalk, or Maestricht beds, wei-e deposited, 

 and theii' powerful jaws, ai-med with great grooved, recurved, 

 conical teeth, their vei'tebrje and various other skeletal remains 

 have been obtained from St. Peter's Mount, near Maestricht, 

 Holland, and from the Chalk of Norfolk and Kent. Remains 

 of over forty species have been found in the Cretaceous rocks 

 of New Jersey, Kansas, &c., in North America. One of 

 these, the Mosasaurus princeps, is computed to have been 75 to 

 80 feet long. The paddles, which were four in number, each 



