291 



outer side concave in vertical as well as transverse section. The inner lace 

 is also concave, with narrow symphyseal plane along inner border. The 

 apical column is an oblique lamina. The maxillaries are narrowed and trun- 

 cate in front ; the areas are large, especially the posterior. The superior 

 groove is deep, and the outer face extensive and longitudinally ridged. 



A specimen from Medford, New Jersey, resembles the others, but is 



only half the size. 



Measurements. 



M. 



Total length i 0.135 



Depth at the posterior outer area 0.058 



Depth at the anterior outer area 0. 040 



Depth at the middle of the beak 0.023 



Width behind at the inner angle r 0. 030 



Width at the anterior outer area 0. 030 



Width at the middle of the beak 0.020 



Length of the maxillary 0. 110 



Width at the apex , , 0.017 



Width at the posterior edge of the posterior area, 0. 042 



Depth of the outer face of the maxillary 0. 042 



Eight lower jaws of this Chimteroid are before me, several of them accom- 

 panied by maxillary bones. The eighth is, as before mentioned, from Medford, 

 New Jersey. The others are from the same horizon, greensand of Creta- 

 ceous, No. 5, from Birmingham and Hornerstown. 



Ischyodus mieificus, Leidy. 



Edaphodon mirificus, Leidy, Proceedings of the Academy of Philadelphia, 1856, p. 221 ; Report 

 of the United States Geological Survey, Hayden, I, p. 306, Plate XXXVII, figs. 1-6. 



Six lower jaws of this species, several of them accompanied by maxilla- 

 ries, resemble closely the one described and figured by Leidy, as above. As 

 Leidy represents, the inner, and especially the outer, borders of the beak are 

 not abruptly excavated from the extremities of the dentinal area, but form a 

 line generally uninterrupted. The anterior outer area is not supported on a 

 tuberosity or angle, and is situated well inside the outer border. One speci- 

 men includes all the pieces of the jaws. The premaxillaries are entire. The 

 median and outer borders are thickened, the latter most so ; while the inner 

 concave face is excavated to a horizontal border of a basal thickening that 

 extends from one edge to the other. The marginal dentinal areas are eight 

 in number, the inner and outer larger than the intervening ones. 



The specimens in my possession are from near Barnesborough and Hor- 

 nerstown, New Jersey ; greensand, No. 5. 



