186 The American Geologist. September, 1893 
striae ornamenting the interior of these scars can be detected 
only under favorable light in the smaller Brown specimen, and 
not at all on the larger one. The smaller Huffman specimen 
has at its smaller extremity a lateral diameter of 51 mm. and 
a dorso-ventral diameter of 62 mm. Thenames for the various 
sides are given by way of analogy with the Brawn specimen, 
where the longer diameter is dorso-ventral. The scars of the 
Huffman specimen are also larger and longer on the dorsal 
surface, which establishes another analogy with the Brown 
specimen, and to the latter point is given great weight in de- 
termining the position of the diameters of the shell above 
discussed. Accepting this interpretation, the dorsal scars 
have an average width of 7 to 8 mm. and the lateral scars one 
of 4.5 to 5.5 or sometimes 6 mm. towards the smaller end 
mentioned above. From this it will be seen that at corres- 
ponding diameters of the shell the Huffman specimen has 
much larger scars. On the dorsal surface the lower crescentic 
border of the scars is more strongly curved; as a result the 
relative length of the scars of this area as compared with 
their width is greater than in the case of the scars on the 
lateral sides. Their average length on the dorsal side is 5.5 
to 6.5 mm., ranging as low as 5 and as high as 7 mm. Their 
average length on the lateral faces is 3 to 3.5 mm., varying 
occasionally to -1 or 4.5, rarely 5 mm. The result is a more 
rhombic appearance of the scars on the dorsal surface: a 
feature to which especial attention is called, since reference 
will be made to it again in relation to the true interpretation 
of the Eaton Glyptodendron. 
The surface ornamentation of the Huffman specimen is very 
distinct. The interior area of the scars is always depressed 
beneath the level of the defining crescentic ridges. These 
ridges are alwa} T s most distinctly defined along their upper 
side. Their definition along the lower side is also usually good, 
except towards the middle where they meet the crescentic 
ridges of the next lower laterally applied scars. Here the 
depressed area of the scars of the vertically lower ( second 
lower) series is often sufficiently elevated above towards the 
aperture to weaken the definition of the bounding ridges near 
the middle of their lower sides. The depressed interior area 
of the scars is traversed by rather coarse stria- of which 7 to 
