RAYMOND: NEW AND OLD SILURIAN TRILOBITES. 23 



The pygidium is considerably longer and more convex than the cepha- 

 lon, and the axial lobe is evidently very wide and without very strong 

 dorsal furrows. 



The dorsal furrows of the cephalon fade out just before reaching the 

 pits in front of the eyes, but this is probably an individual variation. 

 These pits are not directly in front of the eyes as in most species of 

 Bumastus, but considerably inside the projection of a line drawn 

 through the length of the eye. 



The pygidium is very convex, with concave slopes to the lateral 

 and posterior margins. 



Formation and locality: — The type, M. C. Z. no. 650, is from Russia 

 (Newport), Herkimer Co., New York. The horizon is the Leray- 

 Black River (Ordovician). 



ACTINOLOBUS AMERICANUS, Sp. UOV. 



Plate 1, fig. 4, 5. 



The M. C. Z. contains a single pygidium which, on account of its 

 great length and wide flat border, is referred to Actinolobus, a genus 

 previously unrepresented in this country. The specimen is damaged 

 on the right side and has been restored in plaster. 



There is also a break on the left side not shown in the figure, but 

 the outline is believed to be accurate. The specimen is 38 mm. long 

 and 20 mm. wide at the front. At the widest part, the border has a 

 width of 10 mm. and is somewhat concave. The central part of the 

 pygidium is strongly convex. The anterior margin indicates that the 

 axial lobe of the thorax was wide, though not so wide as in the species 

 of Bumastus found with it. 



Formation and locality: — From the Racine dolomite at Racine, 

 Wisconsin. 



LICHADIDAE Hawle and Corda. 



Trochurus nasutus (Weller). 



Plate 3, fig. 1, 2. 



Dicranopeltis nasuta Weller, Bull. Chicago acad. sci., 1907, no. 4, pt. 2, p. 240, 

 pi. 22, f. 5-7. 



A figure of the specimen of this species in the Day collection is 

 introduced in order to show the wav in which the frontal lobe of the 



