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there were technical difficulties of no small magnitude involved in their 

 preparation. 



Those who have engaged in similar detailed studies of other groups 

 of animals can well appreciate the enormous amount of detailed work 

 necessary to bring a publication such as this from the press. The neces- 

 sity for checking and cross-checking of data, over and over again is 

 depressing labor, yet in this case it seems to have been very thoroughly 

 done. A thorough examination of the portions dealing with Pacific Coast 

 species afforded very little opportunity for criticism. On page 14 the 

 names Porella cyclopea and Idmonea clarki are listed from the Pleistocene 

 of Santa Monica, California, but descriptions under these names do not 

 appear in the body of the paper. The latter, however, is described under 

 the name Filisparsa clarki. 



G. Dallas Hanna 



Die Ichthyosaurier des Lias und ihre Zusammenhange. By Friedrich 

 VON HuENE. Berlin. Gebriider Borntraeger, 1922. Pp. 

 114, pis. 22. 



A treatment of the Ichthyosauria as a whole has never been attempted 

 before. The greater part of the literature on this interesting group of 

 marine reptiles has been devoted to the description of specific forms 

 (usually under the blanket name of 'Ichthyosaurus"), and the taxonomy 

 and phylogeny of the group have remained in a chaotic condition. 



This deficiency is removed to a great extent by the present work of 

 von Huene. Although dealing primarily with Liassic forms, those of 

 other formations are reviewed and the taxonomy revised, while a large 

 number of figures and a comprehensive bibliography add to the value of 

 the volume. The stratigraphy of the Liassic ichthyosaur beds is dis- 

 cussed. Of especial interest is a description of the development of 

 Stenopterygius from an j 8-centimeter embryo to a 3-meter adult. 



The division into longipinnate and latipinnate t3qDes, suggested by 

 earlier writers, is developed. Von Huene believes that the entire order, 

 except for a few early forms, may be divided into two phylogenetic 

 series on this basis. 



The author lists a large number of characters common to ichthyosaurs 

 and Mesosaurus; but perhaps it might be better to await further fossil 

 evidence before definitely uniting the two. Von Huene derives the 

 common stem of ichthyosaurs and mesosaurs directly from the embolo- 



