184 BRITISH PALASOZOIC FOSSILS. [Crusracua, 
convex space on each side, separated at base by a portion of the glabella as wide as their length; surface 
of glabella and cheeks covered with sharp subequal granules (two to three in one line) about their diameter 
apart, the intervening spaces finely granulose ; thoraw, axal lobe one-third wider than the lateral lobes, each 
axal segment of the thorax and pygidium with about nine granules nearly as large as those of the head, 
mixed with several irregular smaller ones: side lobes of thorax and anterior part of pygidium with about 
seven or eight rows of large, and several irregular smaller granules, about the size of those of the axal lobe; 
pygidium semielliptical, one-fourth wider than long, axal lobe rather abruptly narrowed from the axis of 
the thorax, about as wide as the lateral lobes, composed of about twelve segments, lateral lobes with ten 
segments. Average length one and half inches, width of glabella four lines, of axal lobe of thorax nearly 
four lines, middle of axal lobe of pygidium three lines. 
Position and Locality.—Extremely abundant (with head, thorax, and abdomen in contact) in the rotten- 
stone of the carboniferous limestone of Derbyshire. 
