2 
never ceased to grow from his writings, and the technique was worked out 
by Dr. C. Hart Merriam, chief of the Biological Survey, United States 
Department of Agriculture, from 1885 to 1910. 
The invertebrates (animals without a vertebral column) are more 
numerous and generally more easy to preserve than the vertebrates, but 
cannot be treated at length in this bulletin. However, as thorough field 
studies of vertebrates involve the collection and preservation of specimens 
of invertebrates, the student is advised to study a good textbook on 
ecological laboratory methods (Wight, University of Michigan, 1938, and 
others) . 
“Directions for Collecting and Preserving Insects” (McDunnough, 
1928) may be obtained by application to the Dominion Entomologist, 
Science Service, Department of Agriculture, Ottawa. Small molluscs may 
be preserved in ethyl (grain) alcohol, but acids in some kinds of denatured 
alcohol (methyl hydrate) are apt to dissolve the calcium in the shells if 
they are immersed for any length of time. Large shells are usually cleaned 
of animal tissue and dried. Marine invertebrates of other orders, as 
well as land worms, slugs, etc., are generally preserved by immersion in 
alcohol or formalin, unless intended for histological or special biological 
investigations, when other methods may be used to prevent shrinkage of 
delicate tissues. The strength of the preservatives must be carefully regu- 
lated for the different classes of specimens ( See section on “Preservatives, 
page 128). 
The progress in the study of mammals may be judged by the fact 
that only about 150 species were known in North America a little over 
100 years ago (Harlan, 1825), whereas the latest complete check-list 
(Miller, 1924) gives 2,554 forms inhabiting North America. Richardson 
(1829) listed 82 mammal species from British North America, and Tyrrell 
(1888) 137 species and varieties from Canada, whereas the latest Catalogue 
of Canadian Recent Mammals (Anderson, 1947) lists 594 species and sub- 
species of mammals known to occur north of the southern boundary of 
Canada, in addition to 2 introduced species and 49 of hypothetical 
occurrence. 
The fact that a very large number of forms have been described and 
listed does not mean that our knowledge of them is complete in any case. 
Often a form has been described and named that appears to differ from all 
others, but only very few specimens may have been observed, and we are 
almost entirely in the dark concerning the extent of its range, its life 
history, economic value, or significance in the fauna of the country. All 
the larger mammals of Canada on account of their value as food or as fur 
producers, or because of their predatory habits, are without doubt known in 
a general way, and there is small probability of any new species being 
discovered. There are, however, local differences in some forms, due to 
geographical environment, that are worth studying, and few of our museums 
have really adequate numbers of specimens from the various regions. The 
differences in many cases are not readily apparent until specimens from 
different regions are brought together. With the advance of civilization 
and settlement most of the larger forms of animal life are rapidly dis- 
appearing all over the world, and many forms have become totally or 
nearly extinct* within the memory of people now living. The necessity of 
obtaining adequate representatives of these rapidly disappearing animals 
