ISBN: 9781154051537

This historic book may have numerous typos, missing text or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1873. Not illustrat… Plus…

This historic book may have numerous typos, missing text or index. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. 1873. Not illustrated. Excerpt: ... Genus MACRODON, Lycett. Machodon Delioatus, M. and W. PI. 26, Fig. 3. Uacrndii a delieahia. Meek and Wokthen, 1870. Proceed. Acad. Natural Sci., Phila., p. 40. Shell small, about twice and a-half as long as high, moderately convex, elongate rhomboidal in outline, posterior margin obliquely truncated, so as to be angular at the base; cardinal margin about three-fourths the entire length, and nearly parallel with the base; anterior extremity very narrowly rounded; basal margin nearly straight along the middle, but rounding very gradually upward anteriorly; beaks depressed, and placed about one-fourth the entire length of the valves behind the anterior extremity; posterior umbonal slopes subangular from the beaks obliquely backward and downward, to the sharply rounded or subangular posterior basal extremity, while the spaces behind and above these slopes are compressed or slightly concave. Surface marked by small ridges and lines of growth, which are crossed by raised radiating lines or linear costa?, rather widely separated posteriorly, but more closely arranged, and less strongly defined towards the front part of the valves. (Cardinal area, hinge and muscular impressions unknown.) Length 0.45 inch; hight, 0.19 inch; convexity about 0.11 inch. This little shell will be readily distinguished from its associate, formerly described by us under the name M. tenuistriatus, by its much more oblique and less gibbous form; but more especially by having its linear radiating costaj separated by wide intervening spaces, instead of being closely crowded together. We know of no species with which it could be confounded. Locality and position--Springfield, Illinois. Upper Coal Measures. Macrodon Tenuistriatus, M. and W. PI. 26, Tig. 4. Macrodon tenuittriala, Meek and Wokthkv, 18... Illinois. State Geologist, Books, History, Geological Survey of Illinois (Volume 5) Books>History <