RAYMOND: BOM1 \i u ORDOVICIAN TRIL0BITE8. 287 



HOMOTELTJB tJLRICHI, sp. iiov. 



Outline of entire Animal oval, whole surface rather evenly convex, the eyes 

 being the only conspicuous prominences. Cephalon and pygidium about 

 equal. 



Cephalon twice as Wide afl Ipng, nearly semicircular, hut since the outline 

 conies just within the semicircle passing through the anterior point and genal 



angles there is a suggestion of triangularity. The glabella is smooth, not 



differentiated. On an occasional specimen there are two pairs of pits between 

 the eyes, the vestiges of two pairs of glabellar furrows. The neck-furrow is 

 practically obsolete and just in front of its normal position is a very small 

 median pustule. The dorsal furrows are very faint except on crushed speci- 

 mens. The eyes are small, strongly elevated and far apart. The palpebral 

 lobes are small, concave on top and so short that a part of the visual surface 

 looks upward. The genal angles are rounded and the sides of the cheeks 

 have a narrow flattened and striated border which stands at an angle with 

 the general surface and is turned downward at the sides and front. This 

 joins the nearly horizontal doublure in a sharp edge. 



Axial lobe of thorax wide, but less than one half the entire width. 



Pygidium not quite twice as wide as long, the narrow axial lobe faintly 

 but definitely outlined, most prominent at the posterior end. Pleural lobes 

 smooth. 



Measurements: — The entire specimen selected as the type is 58 mm. long 

 and 33 mm. wide at the genal angles. The cephalon is 18.5 mm. long, the 

 eye 5 mm. long, and the back of the eye 6 mm. from the posterior margin 

 of the head. The thorax is 20 mm. long, 32 mm. wide at front and 32 mm. 

 wide at back. The axial lobe is 15 mm. wide at front and 13.5 mm. wide at 

 back. The pygidium is 19.5 mm. long, 32 mm. wide at the front. The 

 axial lobe is 15 mm. long. 



Ilomotrlus obtusm (Hall) of the Chazy differs from this species in 

 having more strongly impressed furrows and particularly in its very 

 conspicuously punctate shell. Homotclus simplex (Narraway and 

 Raymond) is much more closely like the present one but has the eyes 

 larger and further back, more traces of ribs on the pygidium, and 

 lacks the angulated border on the cephalon. 



Horizon and Locality: — This species seems to be quite common 

 in the Eden in the vicinity of Cincinnati, Ohio, but as the specimens 

 are all in the Dyer collection I have no data on either exact horizon or 

 locality. Cotypes M. C. Z. 1,575, 1,576. 



