6 MEMOIRS OF THE UNIVERSITY OF CALIFORNIA. 



through the unflagging interest of Miss Annie M. Alexander, who has fur- 

 nished the financial support for nearly all of the expeditions, and has most 

 energetically assisted in insuring their success. The largest share of the direc- 

 tion of field work has been carried by Mr. E. L. Furlong, who has also prepared 

 and mounted practically all of the specimens represented in the illustrations of 

 Californian material in this paper. 



In the initial stages of the work the writer was greatly indebted to Presi- 

 dent Benjamin Ide Wheeler of the University of California, through whose 

 support it was made possible to extend the scale of the investigation so as to 

 cover the broader field of the evolution of the Ichthyosauria as a whole. 



In the field work carried on in connection with the investigation of the oc- 

 currence and age of the Triassic ichthyosaurs, the writer has been particularly 

 indebted to Professor James Perrin Smith, whose knowledge of the inverte- 

 brate faunas has furnished a most valuable basis for con-elation. 



While working on the Ichthyosauria the writer has on several occasions 

 visited nearly all of the American museums in which material of this group is 

 available. The principal collections of European Jurassic ichthyosaurs have 

 also been reviewed, and most of the described specimens from the European 

 Triassic were examined. 



In the course of this investigation the writer has been indebted to a num- 

 ber of the principal museums of this country and of Europe for the use of com- 

 parative material. For courteous co-operation in farthering the work of com- 

 parison, the writer is especially grateful to Dr. A. Smith Woodward and Dr. C. 

 W. Andrews of the British Museum of Natural History; to Professor E. Fraas 

 of the Konigliches Naturalien- Cabinet in Stuttgart ; and to Dr. F. von Huene 

 and Professor E. Koken of the Geologisch-mineralogisches Institut in Tubin- 

 gen. The use of several valuable specimens in the museum of the Polytechni- 

 kum at Zurich, was kindly permittedby Professor Albert Heim; Dr. W. J. 

 Holland kindly allowed the use of a photograph of the remarkably complete 

 ichthyosaurian specimen in the collections of the Carnegie Museum. In work- 

 ing over the subject of evolution of the Ichthyosauria as a whole, the use of the 

 collections of Baptanodon material in charge of Mr. W. H. Reed at the Uni- 

 versity of Wyoming, and of the types described by Mr. Gilmore at the Carnegie 

 Museum, has been particularly helpful. 



The majority of the drawings represented in the plates, also a number of the 

 text figures, were prepared by Mrs. Grace Ballantine. The larger portion of the 

 text figures and several of the plates, including most of the representations of 

 vertebrae, were drawn by Mr. A. J. Heindl. 



JOHN C. MERRIAM. 

 UNIVERSITY OP CALIFORNIA, 

 FEBRUARY, 1908. 



