Paleontology 61 



No. 75. HAY, OLIVER P. The Fossil Turtles of North America. Quarto, iv-f-568 

 pages, 113 plates, 704 text figures. Published 1908. Price $9.00. 



This work has for its purpose the careful description of all the species of fossil 

 turtles of North America that were known to exist at the time of publication. In 

 all 266 species are described and, with few exceptions, figures are given of all of 

 these. Of the 266 species 76 are regarded as hitherto undescribed. The classifica- 

 tion of the order is discussed and the families and genera are carefully defined. 

 Before entering on the consideration of the fossil forms the osteology of most of 

 the living families is elucidated. The modifications undergone by the turtles since 

 their earliest appearance are discussed, as well as the derivation of the order and 

 its various families. There is a chapter on the geographical distribution of the 

 living turtles, illustrated by 8 maps. Two tables present the geological distribution 

 of the North American extinct species. This work is of interest to all students of 

 these reptiles, as many of the genera here described still exist. 



No. 34. WIELAND, G. R. American Fossil Cycads. Quarto. 



Vol. I. Structure, vm+296 pp., 51 pis., 141 figs. Published 1906. Price $6.25. 



Vol. II. Taxonomy, vn+277 pp., 58 pis., 97 figs. Published 1916. Price $6.25. 

 In volume I record is made of the discoveries and collections of silicified 

 cycads. Some of the more important finds noted were made by the author. These 

 include the most remarkable of the branched forms. The various conditions of 

 fossilization and methods of treatment, including the cutting of large thin sections, 

 are taken up. The foliage of the Cycadeoids is determined from the young crowns 

 of partially emergent fronds and compared with that of the existing cycads, some 

 new facts about the latter being brought out. The ovulate fructification is de- 

 scribed in much detail, and the discovery of the bisporangiate flower buds is set 

 forth on the basis of completely illustrated serial sections. The subject of young 

 fructifications is dealt with in preliminary form. There is thus given a redintegra- 

 tion of the long problematic Cycadeoid type. This part of the work affords a key 

 to the study of many hitherto scantily known fossil casts and imprints of Cyca- 

 daceous affinity. The closing chapters are devoted to a thoroughly illustrated com- 

 parative study of the habitus and structure of the existing cycads and to a new 

 theory of angiosperm descent from hypothetic types little remote from the early 

 Mesozoic Cycadeoids. 



In volume II the structure of the Cycadeoids is taken up from the viewpoint of 

 classification and nomenclature. Trunk structure is further considered on the 

 basis of large polished transverse and longitudinal, and also thin sections. Notes 

 are given on nearly all the more important American species, and the necessary 

 comparisons with European forms are drawn. The aim is to give in clear and 

 usable form the present status of Cycadeoid study. Incidentally many new details 

 of both structural and general biologic interest are illustrated. In particular the 

 remarkable monocarpic species Cycadeoidea dartoni is described. As in volume 1 

 extended comparison with existing cycads was made, so in volume II a well-illus- 

 trated account of the related Mesozoic Cycadophytan stem, leaf, and fruit im- 

 prints, and casts is appended. This in large part rests on the author's own dis- 

 coveries in the Liassic of Mexico. A fuller account of the seeds is given, and new 

 theories of seed and floral constitution are discussed. The descent of the angio- 

 sperms is further considered. The two volumes therefore constitute a treatise on 

 the Cycadeoids setting forth all the main features of the group thus far discovered. 

 Both volumes are profusely illustrated and contain the necessary bibliographies. 



