480 GEOLOGICAL SURVEY OF THE TERRITORIES. 



ASAPHUS (Megalaspis *?) GONiocERCUs, -Meek. 



Pygidium rather small for a species of this genus, moderately de- 

 pressed, trigonal in outline, with breadth and length about as 7 to 9; 

 posterior lateral margins slightly convex in outline, and converging 

 rapidly to the posterioi- extremity, which terminates in an abruptly 

 attenuated, slightly recurved, pointed projection, the under side of which 

 is flat, and the upper convex ; mesial lobe much depressed, or very 

 slightly higher than the lateral, and quite obscurely defined by the 

 nearly obsolete dorsal furrows, about three-fourths as wide anteriorly 

 as the lateral, and tapering backward and becoming obsolete before 

 reaching the posterior extremity, in internal casts showing sometimes 

 faint traces of nine or ten very obscure segments ; lateral lobes gently 

 convex, and sloping off gradually to an obscure undefined furrow, or 

 shallow impression, near the posterior lateral margins, which are thus 

 made to appear as if provided with a slightly-depressed border, usually 

 appearing quite smooth, or with faint traces anteriorly of one or two 

 segments, but in some specimens, when examined carefully in an 

 oblique light, traces of six or eight segments may be seen. Surface 

 smooth. 



Length of pygidium, 0.74 inch j breadth, 0.94 inch j convexity at the 

 front, 0.16 inch. 



The only part in the collection known to belong to this species is the 

 pygidium. This is very remarkable for its trigonal form and jiointed 

 posterior extremity, much as we see in Dalmanites. It wants the 

 usually well-defined dorsal furrows and segments, however, of that 

 genus ; which smoothness gives it the aspect of Asaplms. The specimens 

 from which the description was drawn up are probably young indi- 

 viduals, as there are fragments in the collection of an Asaphus of larger 

 size that may belong to this species. If an Asa/phus at all, the form of 

 its pygidium would indicate relations to the group Megalaspis, one 

 species of which {M. heros, Dalmann, sp.) has a similarly-formed 

 pygidium, but with more numerous and very much more strongly-defined 

 segments. I am not aware, however, that any si^ecies of that group has 

 hitherto been found in this country. 



Locality and position. — Near Malade City, Utah, from Lower Silurian 

 beds of the age of the Quebec Group. Professor Bradley. 



Bathyurus seeeatus, Meek. 



Cephalic shield rather distinctly convex, semicircular, being nearly 

 twice^as wide as long, regularly rounded in front, straight across behind, 

 and having the posterior lateral angles terminating in small, short, back- 

 ward-pointing spines ; lateral margins provided with a narrow, slightly- 

 thickened border, (sometimes becoming nearly obsolete just in front of 

 the glabella,) defined by a shallow narrow furrow. Glabella quite con- 

 vex, with its highest part near the middle, strongly defined by the dorsal 

 furrows, cylindrical in form, extending very nearly to the anterior mar- 

 gin, and apparently without lateral furrows ; neck-segment well defined 

 by a distinct furrow passing entirely across, distinctly arched upward 

 and a little backward in the middle, where it bears a small tubercle, or 

 possibly sometimes a short little spine, directed upward and backward; 

 continuation of neck-furrow along the posterior margin of cheeks rather 

 wide and deep ; fixed cheeks comparatively wide and convex, but lower 

 than the glabella, rounding off rather abruptly laterally. Eyes of mod- 

 erate size, but little arched, ranging nearly parallel with each other; 



