MAMMALIA. 



39 



The lower molars of the M. are narrower than the upper, and the grinding 

 surface of the latter describe in their longitudinal direction a slight convexity, while 

 the former have a corresponding concavity. In the upper molars the inner range 

 of tubercles are most worn ; in the lower ones, the outer range. By these marks 

 a detached grinder may be referred to the jaw and ramus supporting it.* 



The M. giganteus (M. Oliioticus of Blum.) is the most common species in the 

 United States. The transverse ridges of its grinders are in shape more like those 

 of the Diiwtherium than in any other Mastodon. The penultimate and antepen- 

 ultimate grinders are three-ridged, making it a Trilophodon in Falconer's arrange- 

 ment. The lower jaw has two tusks in the young of both sexes ; these are soon 

 shed in the female, but one of them (usually the right) is retained by the male. 

 The upper tusks are retained in both sexes ; they are elliptical, and are less 

 obliquely curved than in the Elephant. This fossil head of a young animal was 

 taken from a marsh (Pleistocene) near Newburg, N. Y., and is now in Dr. War- 

 ren's Museum, Boston. It contains two unworn molars in each ramus. 



Size, 28 x 23' Price, with mountings, $20.00. 



No. 147. Mastodon giganteus, Cuv. 

 Lower Jaw of No. 146. 



Size, 24 x 14. Price $6.00. 



No. 148. Mastodon giganteus, Cuv. 



SKtTLL. This, one of the largest elephantoid skulls that has ever been dis- 

 covered, and known as the " Shawangunk Skull," was disinterred from a Post- 

 Glacial fluviatile deposit in Orange County, N. Y. 



Size, 3 ft. 9 in. x 2 ft. 8 in. Price, $30.00. 



