This incredibly detailed work is officially termedThe Viviparous Quadrupeds of North America. These mammals of North America were published in three volumes, dating 1845, 1846, and 1848. Somewhat more that 303 Imperial sets were printed. These are rare and very valuable today. These lithographs were printed on paper sized at22 x 28 inches, termed the imperial size, and also defined as the elephant size. (Note that this is smaller than thedoubleelephant size of 27 1/2 x 39 1/2 inches.) Besides the size, these prints are identified by the legend at the lower right "Lith. Printed & Cold. by J.T. Bowen, Phila."