46 REPORT OF THE SECRETARY. 



iug Alaska. Prof. A. E. Yerrill, Prof. S. I. Smith, and several otbei 

 naturalists are still engaged as collaborators upon Fish Commission 

 collections, some of which have been transferred to the Museum during 

 the past year, while others are exi)ected at an early date. Large num- 

 bers of duplicate specimens have been distributed to institutions of 

 learning throughout the country. 



XII. JJejjartmcnt of Comparative Anatomy. — The work in this depart- 

 ment, of which Mr. P. W. True is curator, is at present confined to a 

 development of the osteological collection which is already of consider- 

 able dimensions and occupies one of the entire exhibition halls. The addi- 

 tions to this department have been comparatively few, the steady in- 

 crease in the exhibition series of material being the result of cleaning and 

 mounting skeletons which had come into the Museum in previous years. 



Attention has been directed especially to obtaining skeletons of thor- 

 oughbred domestic animals, and a considerable number of specimens 

 representing the important breeds of dogs, have been obtained during 

 the year. In this series a single case is devoted to the comparison of 

 the vertebrse of the different, groups of vertebrates. Of the cervical 

 vertebrte a considerable number of typical forms have been j)laced side 

 by side ; in another series the dorsal, in another the caudal vertebrce. 

 Another part of the series shows the limbs of the vertebrates arranged 

 so that their parts can be readily compared. In still another case is ex- 

 hibited the structure of bones and the teeth, and so on through the en- 

 tire structure of the skeleton. 



A card catalogue of the skeletons of the mammals, which constitute 

 the greater bulk of the collection, has been completed. 



XIII. Department of Invertebrate Fossils — (A) Paleozoic Section. — Mr. 

 C. D. Walcott, of the Geological Survey, honorary curator, reports that 

 the collection now contains over 80,000 specimens, of which 7,833 have 

 been added during the year, a large portion of this material having 

 been transferred from the Geological Survey. The collection has been 

 personally arranged by him during the two years of his connection with 

 the Museum, and is now contained in sixteen table-cases in one of the 

 I)rincipal halls of the Museum. Nothing has yet been exhibited, but as 

 soon as cases shall have been i)rovided, a very interesting series already 

 selected may be placed upon view. Mr. "Walcott's attention is at present 

 especially directed to the formation of a systematic collection of the 

 Cambrian fossils of the United States, as well as for securing a study 

 collection from typical localities in the Lower Silurian and Devonian 

 formations. 



The special research upon w^hich Mr. Walcott is engaged in behalf of 

 the Geological Survey is the study of the stratigraphy and paleontology 

 of the Cambrian system of North America, During the past year the 

 results of a preliminary study of the Middle Cambrian was published 

 as Bulletin 30 of the U. S. Geological Survey. 



