18 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1907. 
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 state 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- 
erles or oune information of current interest in all departments 
of science. 
In the Seon 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 Synaptidee and Molpadiide 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 
LV, have been completed. Among the recent papers published in this 
series is a “ Letter of Dr. Diego Alvarez Chanea,” 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- 
