Page:Popular Science Monthly Volume 20.djvu/143

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form a division of the Protozoa, and consist, essentially, of a soft mass of clear or granular protoplasm, usually colorless, with one or more nuclei and contractile vesicles. They are mostly microscopic, are quite common, and may be found in the settlings of still water, in the slime of submerged rocks, stems, and leaves, and in similar situations. The author hopes, by means of this work, which is devoted to the description of genera and species, to facilitate the study of these interesting organisms.

Hocking Valley coal-field of Ohio occupies an area of about two hundred and fifty square miles, in the region drained by the Hocking River, and is characterized by the exceptional thickness and value of its coal-beds. It contains, also, extensive beds of good iron-ores and quarries of limestone, and thus combines rare advantages to encourage the establishment of iron-works. It is well supplied with railroads connecting it with important commercial centers which can be supplied with coal more conveniently from it than from any more distant source. All of these points are set forth clearly and in detail in the present report.

intended to awaken interest in the study of butterflies, and to assist in intelligent observation. It begins with the life-history of the insect, from the egg through the stages of the caterpillar, the chrysalis, and the perfect insect; describes its internal organs, with careful illustrations of its anatomy, its habits in all its stages, its seasonal changes and histories, and its coloring, "with further histories," and discusses the diversity of the sexes in coloring and structure, the origin and development of ornamentation, the ancestry and classification and geographical distribution of butterflies, and suggests a theory of the way in which New England was colonized with the insects. In the appendix are given instructions for collecting, rearing, preserving, and studying butterflies, the bibliography of the subject, and a systematic list of butterflies mentioned in the text. The whole is fully illustrated, generally from American specimens.

title of this book describes in the fullest manner its contents. Dr. Abbott has wisely chosen to limit his work to that portion of the continent in which he has collected and studied, and to which he has added so many valuable contributions. In the preface he expresses the hope that the book will "induce others to explore such localities as they have opportunity of doing, and to preserve such traces of early man as they may find by placing them in public museums." Dr. Abbott has strictly adhered to this advice. He has no private collection. The immense mass of material he has gathered in his State now enriches the museums of Cambridge and Salem, where at all times it is open to inspection. In the light of the author's exhaustive study of the Trenton gravels, and the various beds superimposed upon them, we think he is justified in taking exception to the views expressed by Professor Whitney that "it is evident that there has been no unfolding of the intellectual faculties of the human race on this continent which can be parallelized with that which has taken place in Central Europe. We can recognize no palæolithic, neolithic, bronze, or iron ages." Dr. Abbott shows conclusively that the evidences of a