20 REPORT OF THE SECRETARY. 



and connexion with nerve cells, the connexion of the nuclei with 

 each other by nerve fibres passing from the roots and from the nerve 

 cells, the structure of the olivary bodies which possess a peculiar 

 iuterest from their resemblance in convoluted structure to the cere- 

 brum and cerebellum. 



3d. An attempt to show, notwithstanding the apparent difference of 

 structure between the spinal cord and medulla oblongata, a difference 

 which appears very considerable at first sight, that the plan of struc- 

 ture of the two is identical, that the general arrangement of parts 

 strictly corresponds, that the relation of the nerve roots to their 

 nuclei or cell groups is the same, and moreover the connexion estab- 

 lished between the different nuclei is carried out on the same plan. 

 The illustrations for this work were taken by the author himself 

 directly from the microscopic dissections by photography. For the 

 general edition the photographic illustrations have been copied on 

 stone with great care by L. IT. Bradford. The steel plates were en- 

 graved by J. W. Watts. Besides these, a limited number of photo- 

 graphic prints from the original negatives have been prepared by 

 Dr. Dean himself for private distribution, and from these negatives 

 other copies may be obtained either on direct application to the author 

 or through the medium of this Institution. 



This paper, which is the result of over two years of constant study, 

 was referred to Dr. TV. A. Hammond, of the United States army, 

 and Professor Jeffries Wyman for critical examination, and was recom- 

 mended by them for publication as a valuable addition both to human 

 and to comparative anatomy. 



The third paper accepted for publication is on the Paleontology 

 of the Upper Missouri, by F. B. Meek and F. V. Hay den. 



This work contains figures and descriptions of all the known inver- 

 tebrate fossil remains of the various geological formations of Idaho, 

 Dakota, Nebraska, and portions of Kansas. About 370 species, 

 nearly all of which are new, are fully described, and the descriptions 

 are accompanied by remarks on the relations of each species to allied 

 forms from other districts in this country and Europe, both living and 

 fossil — its geological range, geographical distribution, &c. The illus- 

 trations consist of about one thousand carefully drawn figures, occu- 

 pying forty-five quarto plates. 



In addition to full descriptions of species, the work also contains 

 extended accounts of all the genera to which these fossils belong, with 

 the synonymy of each genus, and remarks on its affinities to other 

 genera, both living and extinct ; and assigns the probable period of 



