14 .MMMOIRS OF THE UNIVERSITY OP CALIFORNIA. 



Not until the Upper Triassic is reached in Europe do we find ichthyosaurian 

 remains which give more than suggestions as to the true nature of the forms 

 in the Triassic which they represent. The most abundant and important Trias- 

 sic ichthyosaur material known in Europe is that from the bituminous shales of 

 Besano in the vicinity of lake Lugano in northern Italy. This horizon has been 

 stated to be the equivalent of the Raibl.' The Raibl is referred to the Upper 

 Trias,' but more recent investigations have seemed to show that this horizon may 

 be somewhat older. The material comprises a number of finely preserved 

 skeletons exhibiting practically all parts of the skeletal structure. In addition 

 there are a number of isolated parts of skeletons which help to interpret some 

 of the larger specimens. On this material Bassani (1886) based Ichthyosau- 

 rus cornalianus, which later became the type of Baur's (1887) genus Mi.ro- 

 saurus. 



From the Rliaetic portion of the Upper Trias Sauvage (1876) has described 

 fragmentary remains apparently representing two species of primitive ichthyo- 

 saurs, Ichthyosaurus rhacticus and /. ( ?) carinatiis. Vertebrae are also known 

 from the Swabian Bonebed (von Huene, 1902) and from the Koessner bed of 

 Achnerthal (von Meyer, 1856). FromRhaetic beds near Bristol, England, a 

 number of ichthyosaurian remains are also reported (Phillips, 1871). 



Spitsbergen. The occurrence of ichthyosaurian remains in the Triassic 

 Spitzbergen was made known by Hulke in 1873 in a short paper on some frag- 

 mentary material obtained by a Nordenskiold expedition in 1864 and 1868. 

 The remains were referred to Ichthyosaurus by Hulke. Later observation by 

 Merriam (1902) and Yakowlew (1902) have shown that Hulke 's specimens 

 were related to Shastasaurus. Dames (1895) supposed them to belong in Mi.ro- 

 saurus, but was unfortunately not well acquainted with the structure of that 

 form, and also misinterpreted the first description of Shastasaiirtis. The orig- 

 inal material of Hulke 's species was lost after being studied by Dames in 1895. 



A good fragment of a vertebra, obtained by the Russian- Swedish expedition 

 in 1899-1901, was described by Yakowlew (1902) and referred to Shastasaurus. 



New Zealand. In 1874 Hector described from New Zealand an ichthyo- 

 saurian vertebra obtained in a micaceous sandstone in the Rangitata district 

 of the province of Canterbury. The formation in which it occurred was said to 

 be identical with other strata considered to be Triassic. 



America. The occurrences of Triassic ichthyosaurians in America have 

 thus far been limited to exposures of the marine Trias in California and Ne- 

 vada (fig. 2). As in Europe, remains are known from both the Upper and 

 Middle Triassic, the oldest known specimens coming from the Middle Trias. 

 The Upper, Middle and Lower Trias are all three represented in California and 



i Bassani, F., Atti Soc. Ital. Sc. Nat., vol. 29. Milano, 1886. 

 - See table on p. 16. 



