Illustrated and described by Dr. Timothy Allen, 10 East thirty-sixth street New York. This is a strictly scientific work; but in these days when a first class microscope is regarded as an essential piece of household furniture in well regulated families as a piano, it is not clear that a strictly scientific work which ministers to this taste, may not be regarded as of a popular character also. The Characeae of all aquatic plants are extremely interesting subjects for microscopic work, as the movements of the fluids can be distinctly seen.