MKHKIAM: TRIASSIC ICIIT1I YOSATKIA. 



HISTORICAL REVIEW OF LITERATURE. 



The earliest reported discoveries of Triassic iclithyosaurian remains were 

 made known by Herman von Meyer and by G. Curioni in 1847. The material 

 available for von Meyer's studies consisted of a few teeth and vertebrae, and 

 an imperfect sketch of a saurian found at Reiflingen in Steyermark in 1843 by 

 Professor Pranger. Von Meyer knew also of a vertebra from Ettersberg near 

 Weimar. These specimens were mentioned by von Meyer principally because 

 of their occurrence in beds considerably older than those in which the typical 

 ichthyosaurs were known. Nothing particularly characteristic was noted in 

 their structure, and the Reiflingen specimen was compared with Cuvier's fig- 

 ured specimens described as Ichthyosaurus platyodon. 



In the same year in which von Meyer announced his discovery of Triassic 

 iclithyosaurian remains, G. Curioni gave notice of the occurrence in the bitu- 

 minous shales of Besano, of a form which he referred to Ichthyosaurus coin- 

 in nn is. 



In 1852 fragmentary specimens from the Wellendolomit of the Black For- 

 est, including a vertebra, some paddle bones, and a jaw fragment with teeth, 

 were described under the name of Ichthyosaurus atavus by Quenstedt. 



In 1855 von Meyer described from the Muschelkalk of Ober-Schlesien a 

 vertebra which resembled a dorsal of an ichthyosaurian. In connection with 

 the description of this specimen reference was made to a somewhat similar ver- 

 tebra described (Palaeontographica Bd. 1, p. 253, Taf. 29, fig. 55) from Larishof 

 in Ober-Schlesien. This vertebra seemed to show a natural perforation of the 

 centrum. Accompanying it there is figured a vertebra with a central perfora- 

 tion of the centrum, and with a broad unexcavated margin surrounding the 

 deeply concave middle region of the articular face. In 1856 von Meyer gave 

 a brief description of two vertebrae from the Koessner beds of Schleimser 

 Joch in Achenthal and noted their resemblance to Ichthyosaurus tenuirox- 

 tris. Up to this time no evidence had been obtained which tended to show 

 that the Triassic forms were materially different from the typical Jurassic 

 ichthyosaurs. 



In 1868, and before the true nature of any European Triassic ichthyo- 

 saurian had been made clear, Leidy described the first known specimens from 

 America. Though the material at Leidy 's command was very fragmentary, 

 the distinguishing characters of the type they represent could have been made 

 out had some of the enveloping limestone been removed. The characters re- 

 ferred to in the original description were principally those of ordinal value. 



