Carhoniferons Trilobites. 99 



Coal Measures ; also Lower Coal Measures of Illinois and Ujiper 

 Coal Measures of Plattsmouth, Nebraska. 



GRIFFITHIDES SANGAMONENSIS, Meek and Worthen. 



PLite III, Figs. 7 & 8. 



PJdllipsia (Griffitliides) Sangamoneims, Meek and Worthen, 1865 ; Proc. 



Acad. Nat. Sci. Phila., p. 271. 

 PhiU'qma (GriffitJudes) aSV/?^,C'«wc^;?«/6'/s, Meek and Worthen, 1873; Palseont. 



Illinois, Vol. Y, p. 615. pi. 82, tig. 4. 

 PliiWpshi Sangamoneiws, Herrick. 1887; Bull. Sci. Lab. Denison Univ., 



Vol. II, p. 61. pi. 5, fig. 18. 



The descrii)tion of this species is given by Messrs. Meek and 

 Worthen in theii- fin.-d re])ort, Palaeontology of Illinois, Vol. V, 

 j). 615, as follows. 



'• EnUre outline elongate subovate. Cephalic shield very convex, forming 

 more than a semicircle, and about one-third wider than long ; regularly 

 rounded in front and straight behind, with posterior lateral angles produced 

 into rather broad, carinated, pointed or subspinous appendages equaling 

 in length the distance from the posterior side of the cheeks to the anterior 

 end of the eyes. Glabella ventricose, very prominent, separated from the 

 cheeks on each side by a moderately distinct furrow, which also passes 

 around the front ; most convex behind the middle, thence rounded and de- 

 clining to the rounded front, about one-fourth longer than wide, and slight- 

 ly wider between the eyes than anteriorly ; sides nearly parallel, but a little 

 sinuous at the middle ; posterior lateral lobes comparatively large, subtrigo- 

 nal or tuberculiform, and entire!}" isolated by the the distinct lateral furrow 

 passing obliquely across with a backward curve, from opposite the middle 

 of each eye, so as to intersect the neck-furrow ; second lateral lobes much 

 smaller and more obscure than those behind, and also oblique, being mere- 

 1}' defined by a faint impressed, curved oblique line ; in advance of these 

 there are also obscure indications of two short, nearly obsolete lateral fur- 

 rows, scarcely visible without the aid of a lens. Occipital segment well 

 defined, but lower and considerabl}" shorter in its transverse diameter than 

 the glabella ; strongly arched upwards (not forwards), and projecting back- 

 wards a little behind the posterior Ime of the cheeks ; neck-furrow distinct, 

 and arched upwards with the occipital, or neck-segment ; its continuation 

 along the posterior sides of the cheeks very deep, and nearly straight for 

 about two-thirds of the way across towards the lateral margins, where it in- 

 tersects another furrow or depression coming around the sides of the cheeks. 

 Eyes lunate, rather large, or nearly half as long as the glabella, exclusive of 

 the neck-segment, prominent, but not as high as the glabella, located about 

 half their own length in front of the posterior margin of the cheeks ; visual 



