18 REPORT OF THE SECRETARY. 



The Smithsonian Contributions to Knowledge, now in their thirty- 

 fifth volume, are restricted to the publication of positive additions 

 to human knowledge resting on original research, all unverified specu- 

 lation being rejected. The Smithsonian Miscellaneous Collections 

 are designed to contain reports on the present slate of our knowl- 

 edge in particular branches of science, instructions for collecting 

 and digesting facts and materials for research, lists and synopses of 

 species of the organic and inorganic world, reports of explorations, 

 and aids to bibliographical investigations. This series is now in its 

 fiftieth volume, and in the quarterly issue provision has been made 

 for the early publication of short papers descriptive of new discov- 

 eries or containing information of current interest in all departments 

 of science. 



In the Smithsonian Contributions to Knowledge several important 

 works are in press. One of these is a memoir on "Glaciers of the 

 Canadian Rockies and Selkirks," by Dr. William H. Sherzer, of the 

 Michigan State Normal College, which is a final report on the Smith- 

 sonian expedition of 1904. A preliminary report on this expedition 

 was published in the quarterly issue of the Smthsonian Miscel- 

 laneous Collections in 1905. There is also a work by Prof. E. A. 

 Andrews, of Johns Hopkins University, on "The young of the cray- 

 fishes astacus and cambarus," giving the results of long and careful 

 observation of the growth of these common animals. 



Prof. Hubert Lyman Clark, of the Museum of Comparative 

 Zoology at Cambridge, Mass., who has been at work for some time 

 classifying and describing the specimens of Apodous Holothurians, or 

 sea cucumbers, in the National Museum — a collection numbering over 

 a thousand specimens from the shores of North and South America — 

 has submitted a report embracing the result of his study on the fami- 

 lies Synaptidse and Molpadiida3 which will appear some time during" 

 the next year. Other memoirs for the series of Contributions are in 

 preparation. 



The quarterly issue of the Smithsonian Miscellaneous Collections, 

 which was temporarily suspended in 1905, was resumed in September, 

 1906. Since then parts 3 and 4 of Volume III, and part 1 of Volume 

 IV, have been completed. Among the recent papers published in this 

 series is a " Letter of Dr. Diego Alvarez Chanca," dated 1494, re- 

 lating to the second voyage of Columbus to America, which was trans- 

 lated and annotated by Dr. Fernandez de Ybarra. This letter is 

 notable as being the first "written document of the natural history, 

 ethnography, and ethnology of America." 



In the regular series of Smithsonian Miscellaneous Collections 

 there has been completed a second paper on the "Attainment of very 

 low temperatures " dealing with the "self -intensive process of liquefy- 

 ing gases." This paper is a report on researches carried on under a 



