498 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



based the Ceratodus GuentJieri of Professor Marsh. On the 

 assumption that the plate belonged to an adult, the species 

 must have been little, if any, larger than the existing JVeoce- 

 ratodus of Australia (see American Journal of Science and 

 Arts (3), vol. xv., p. 70). 



An American Ichthyosauroid Form. 



No remains of reptiles of the family of Iehthyosaurids, or 

 of any related type, had been found in any American forma- 

 tion until the past year. In the last month of that year, 

 however, Professor Marsh announced the discovery of por- 

 tions of the skeleton of a species which agreed in all essen- 

 tial respects with the corresponding parts of Iehthyosaurids. 

 The skull, " in many features," showed a strong resemblance, 

 and "its general form" was the same ; "the great development 

 of the premaxillaries, the reduced maxillaries, and the huge 

 orbit defended by a ring of bony plates, are all present" in 

 the one as in the other. As to other portions of the skele- 

 ton, the vertebrae and ribs " cannot be distinguished from 

 the corresponding parts of Ichthyosaurus" One notable dif- 

 ference, nevertheless, exists betw r een the American reptile 

 and the Iehthyosaurids of the Old World. The jaws " ap- 

 pear entirely edentulous, and destitute even of a dentary 

 groove." On account of this want of teeth, notwithstanding 

 the agreement in other respects, Professor Marsh believes 

 that the American form should be differentiated, even to an 

 ordinal extent, from the IcJithyosauria, and he proposes to 

 call such order Sauranodonta, and names the family Saura- 

 nodontidm, the single species being designated as fSaurano- 

 don nutans. The skull of the discovered specimen was about 

 2 feet long; "one trunk vertebra measures 85 mm. in width, 

 38 mm. in length on the floor of the neural canal, and 21 mm. 

 between the centres of the two rib articular faces of the same 

 side." The length of the entire animal is supposed to have 

 been about 8 or 9 feet. The remains were found in associa- 

 tion with shells of Ammonites and Belemnites, in beds re- 

 ferred to the Jurassic age, and immediately below what has 

 been called, by Marsh, the " Atlantosaurus beds;" and the en- 

 closing strata are proposed to be called the " Sa.uranodon 

 beds." 



The discovery thus signalized is of great interest; but we 



