Monograph of the Cnistacea of the Cincinnati Group. 127 



into long, slender, straight spines, which reach half as far as the 

 pygidium ; glabella very prominent, broad, ovate, finely granulated ; 

 marginal fillet wide, regularly rounded and marked in front by three, 

 four, or five rows of deep, rounded pores or punctures ; these rows in- 

 crease by one or two additional ones on the sides of the shield, and 

 toward the lateral posterior angles are often irregularly scattered. 

 Thorax with six segments ; lateral lobes much wider than the axis. 

 Pygidium three times wider than long, and obtusely mucronate. 



It is extremely rare to find more than the cephalic shield and spines 

 of this trilobite. Specimens showing the thoracic segments, though 

 poorly, have, however, been found at and about Cincinnati. Its range 

 seems to be from the lowest exposure of the rocks in the Cmcinnati 

 Group to about 250 feet above low Avater-mark at Cincinnati. In many 

 places within this range the fragments of the cephalic shield, the 

 punctured fillet and the spines are in great abundance, though good 

 specimens of the cephalic shield and spines are not.very common in the 

 best localities. 



Genus X/c/^rts— (Dalman, 1827). 



Body ovate, very flat ; siuface granulated ; head semicircular ; glabella 

 large, semi-oval, with one long segmental furrow curving inward and 

 clownward from the upper third of the glabella on each side, nearly 

 to the neck furrow, partially inclosing two large oval spaces, and close 

 to the ends of the neck furrow a posterior pair of furrows inclose a 

 very small trigonal lobe on each side ; neck segment broader than the 

 base of the glabella ; cheeks small ; eyes moderately large, reniform ; 

 eye line cutting the outer margin in front of the angles ; thorax of ten 

 segments, j)leura flat, falcate, each with a fine slightly sigmoid pleural 

 furrow, not reaching the margin ; pygidium semi-oval, axis undefined, 

 the latteral furrows, instead of encircling the end, converge about the 

 middle, and diverge again toward the posterior margin, which they do 

 not reach ; tw^o short segments at the anterior convex part ; side lobe, 

 flat, of two broad falcate ribs on each side projecting beyond the mar- 

 gin, each with a fine mesial duplicating groove; middle lobe semi-elhp- 

 tical, pointed, a small divisional line coming ofl" from the middle of the 

 dorsal furrow on each side, curving downward and outward toward its 

 extremity, so as partially to include an oval space on each side." 



Lichas Trentonensis — (Cokrad, 1842). 

 'Buckler ventricose, granulated or pustulate, somewhat fine-lobed ; 



