410 



posterior angles are rounded, and although distinctly defined all round, by 

 the dorsal furrows, (which, however, are only slightly impressed,) the 

 glabella in the anterior half is scarcely at all elevated above the general 

 convexity of the head ; it is moderately prominent behind. The eye is 

 situated at mid-length of the head, semi-annular ; its centre distant from 

 the side of the glabella, two lines, when the length of the head is thirteen 

 lines. 



The anterior margin of the head to front of the glabella is strengthened 

 by a flat rim, which slopes downwards and forwards at an angle of about 

 60, with the horizontal plane of the body. This character is constant in 

 head specimens of all sizes, from a length of six lines to thirteen. The 

 width of this rim in the largest specimens, is one line and one-third. 

 Cheeks, thorax and pygidium, unknown. Surface apparently smooth. 



Length of large head, thirteen lines ; width of glabella at base, nine 

 lines, and at two lines from the front margin, eight lines. 



Limestone, No. 1. 



BATHYURUS DUBIUS. (N. sp.) 



Fig. 390. 



Description. This species differs from B. capax in having the glabella 

 more pointed and more narrowly rounded in front, and the marginal rim 

 not flat but of a sub-cylindrical wire-like form. 



Length of the head in largest specimens seen, nine lines ; width of gla- 

 bella at neck furrow, six lines and a half, and at two lines from front mar- 

 gin, five lines. 



Limestone, No. 1. 



BATHYURUS BITUBERCULATUS. (N. sp.) 



Fig. 391. 



Description. Glabella the same as in B. dubius, but more pointed in 

 front, and with an elongate-oval tubercule or lobe on each side of the pos- 

 terior half. These tubercules are of an elongate oval form, pointed at both 

 ends, bounded on the outside by the dorsal furrow which runs all round the 

 glabella, and on the inside by a shallow, rather obscure groove, but which 

 seems to separate them completely from the main body of the glabella. 

 The lower pointed extremity of each terminates a little below the level of 

 the neck furrrow, and the upper, a little behind the mid-length of the head. 



Length of the largest head seen, eight lines and a half ; width of gla- 

 bella just behind the neck furrow, six lines ; length of each tubercule two 

 lines and a half ; width of same in the middle one line. Surface smooth. 



Limestone, No. 1. 



