Reviews 



Triassic Ichthyosauria, with Special Reference to the American Forms. 

 By John C. Merriam. Memoirs of the University of California, 

 Vol. I, No. I, pp. 1-196, pis. 1-18, 1908. 



Just forty years ago the late Professor Leidy described some fragmentary 

 remains of ichthyosaurs from the Triassic of Nevada, the first known repre- 

 sentatives of the order from America. About ten years later Professor 

 Marsh made known a much more highly specialized form, Baptanodon, 

 from the Jura-Cretaceous of Wyoming, a form which has been recently 

 well described by Mr. Gilmore. Until 1895, nothing was added to our 

 very meager knowledge of the early types from America and not much 

 from other parts of the world. Since that time, however. Professor 

 Merriam, the author of the present memoir, has been engaged almost con- 

 tinuously in the collection and study of the abundant, but often refractory 

 remains of these animals from the Trias of the Pacific region, the final and 

 praiseworthy results of which are embodied in the present work. In 

 addition to the description of Leidy's Cymbospondylus he has founded no 

 less than four other genera, Torotocnenms, Merriamia, Delphinosaurus, 

 and Shastosaurus. Mixosaurus, Ophthalmosauriis, and Ichthyosaurus are 

 the only other known genera of the order, hitherto unknown from America 

 with certainty. 



From the time when Scheuchser two centuries ago made known some 

 vertebrae of an ichthyosaur from Altorf as those of a human being who 

 had come to grief in the Noachian deluge, the gropthe ichthyosaurs have 

 been of special interest to all classes, and much has been written about them 

 in literature both grave and light. So perfectly were they adapted for 

 aquatic life that it had been generally assumed, until 1887, that they were 

 directly derived from the fishes. Baur it was, who, in the year mentioned, 

 showed conclusively from the study of the only, and imperfectly known Euro- 

 pean Triassic form, Mixosaurus, that the animals must have sprung from 

 some terrestrial crawling reptiles. A further knowledge, therefore, of the un- 

 expectedly rich and varied ichthyosaurian fauna which has been brought to 

 light by Dr. Merriam from the Triassic deposits of the Pacific region since 

 1895 when he began his energetic studies of this group, are peculiarly wel- 

 come to all interested in extinct animals and their evolution. So important 

 are the many positive demonstrations of evolution in these forms which the 



775 



