October, 191-3. New Trilobites — Slocom 53 



impressed lines. These lines are most distinct on the doublure and 

 anterior portion of the glabella and rather indistinct on the pygidium. 

 Free cheeks finely punctate. 



Cephalon sublunate in outline, somewhat depressed on the antero- 

 lateral margin, convex, frontal slope inflated but not projecting. Mar- 

 gin marked by a slight recurved elevation; genal angles obtusely 

 rounded; free cheeks large, produced in front of the cranidium nearly or 

 quite to the median line. Eyes small for the genus but prominent, 

 situated at points each one-third the transverse diameter of the cephalon, 

 and about their own diameter from the posterior margin. The facial 

 sutures originate on the posterior margin of the cephalon at about one- 

 third the distance from the dorsal furrows to the genal angles, curve 

 obliquely forward over the palpebral lobes thence in sigmoid curves to 

 the anterior margin, where they meet. Glabella furrows, dorsal furrows 

 and occipital ring and furrow are obsolete on the surface of the test, but 

 on casts the location of the dorsal furrows is indicated on each side by 

 pits at the posterior margin of the cephalon. These pits are connected 

 by a shallow occipital furrow, running parallel to the posterior margin 

 until near the median point, where it arches forward. 



Thorax composed of eight broad, fiat segments, trilobation very 

 obscure; axis about three-fourths the entire width, depressed convex; 

 pleural lobes curving regularly to the lateral margins; segments arched 

 slightly forward on the axial lobe, somewhat curved backward. On 

 enrolled specimens this backward curve appears greater than it really is 

 on account of the flattening of the anterior portion of the pleurae, which 

 originates at the dorsal furrows and gradually widens distally. On the 

 anterior border at the dorsal furrow of each segment are small projec- 

 tions which point forward and fit into corresponding notches of the 

 preceding segment. The segments are without grooves on the test, but 

 on the casts a shallow groove connects the dorsal furrows. 



Pygidium somewhat narrower but longer than the cephalon, de- 

 pressed convex, sloping equally to the margins, trilobation and seg- 

 mentation wanting on the surface of the test but faintly discernible on 

 the casts. 



Remarks. — The Maquoketa specimens, above described, appear to 

 correspond in practically all points to the original description and are 

 from a similar horizon to the type. The Galena and Trenton speci- 

 mens referred to this species and described by Clarke appear to differ as 

 follows: The facial sutures reach the margin of the cephalon in front of 

 the eyes, while in the Maquoketa specimens the sutures reach the 

 anterior margin near the median line of the cephalon. The front part . 

 of the cranidium is more inflated in the Maquoketa specimens. 



