Contributions of the Maclurian Lyceum to the Arts and Sciences, V. 1. No. 1-3 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1827 edition. Excerpt: ...species in this manner of the U. Jluviatilis. There is also a striking resemblance between some of the Unios of the Atlantic States and some species found in our Western waters; thus the U. nassutus of the Delaware, approximates so nearly the U. rectus Lam., often called U. proelongus, of the Ohio, that on comparing a number, we have been almost led to the conclusion that they are merely varieties of the same species, produced by difference of food and locality--they are certainly as much like each other as the U. Jluviatilis of the two rivers. That one should be a much thicker and larger shell than the other is no objection; for we find that those specimens of the Unio taken from deep water, are generally thin and fragile, while individuals of the same species found in shallow and sluggish streams, are much more ponderous--Again, the U. carinifera of Lamark, which is a true Fluviatilis, very much resembles some specimens of the U. alatus in its wing like appendage, though there can be no doubt that this last shell belongs to a distinct species, if not to another Genus. If we were authorized to adopt the theory that some of the described species of Unio generated promiscuously together, most of our present difficulties might be very readily removed. Certain varieties in the contour of many species we know take place in consequence of a preternatural enlargement of the shell in certain directions owing probably to a disease of the animal, which has produced an elongation of his mantle in that direction. The amount of this monstrous growth can be readily determined by the configuration of the impression made by the mantle of the animal on the surface of the nacre, near the margin of the shell. Besides the above regular but preternatural...