Comparison 

 with other 

 species. 



220 



Sculpture. The surface of the test is coarsely granular, but -smoother 

 toward the summit of the ridges and toward the hinge. 



Size. Length 2 mm. ; width 1| mm. ; depth about \ mm. for each 

 valve. 



Horizon and locality. The cal^iferous gray flags of Band C. 2 b, at 

 McLean brook, near Mira River, X. S. Common. 



This species is a link between Beyrichona and Beyrichia ; the general 

 form and moulding of the shell is similar to that of Beyrichona, but the 

 sharp, high ridge at the anterior end is different from any species of that 

 genus. 



It differs from Beyrichia nana, Brogg. of the *Ceratopyge limestone 

 (Temadoc horizon), in its larger size, broader valves, and in having a 

 higher ocular ridge. From B. costata, Linrs. of the Beyrichia lime- 

 stone (Ordovician)f in its greater width and sharp high ridge near the 

 anterior margin. From B. primceva of the Protolenus Fauna J it differs 

 in its smaller size and greater width and in having more prominent lobes. 



TRILOBITA. 



AGNOSTUS TBISECTUS, Salt. mut. PONEPDNCTUS. PI. XVIL, figs. 8a-c. 



Bull. Nat. Hist. Soc. of N.Brunswick vol. iv., p. 278, pi. v. figs Sa-c. 

 Agnostus This form grows to a larger size than the type as figured by Tullberg, 



ix>nepunctus. ' anc * differs in several respects. The reticulation on the head- shield does 

 not show a net-work near the glabella, but detached irregular furrows ; 

 opposite the posterior half of the glabella the ornamentation is scarcely 

 more than small, sparse, irregular pits. The posterior end of the glabella 

 is wider than that of the European form, and there are lateral lobes 

 near the front of the main lobe. 



In the pygidium there are also differences ; the sculpturing of the side- 

 lobes is scarcely more than shallow, open pits, faintly visible, and there 

 is a small tubercle at the end of the rachis, which overhangs the rachial 

 furrow. Examples of the pygidium showing the inner surface, have as 

 many as nine paired pits along the inner furrow of the posterior lobe of 

 the rachis, showing that that lobe is composed of numerous somites. 



Size. The shields of this mutation of A. trisectus attain a length of 8 

 mm. 



* Die Silurisch. Etagen, 2 und 3, p. 55, tab. xn, tig . 15. 



tKongl. Svensk vetenskapsakad. Handl. bd. 8 no. 2, p. 85, tafl., figs. 67, 68. 



t Trans. Roy. Soc. Can., 2 ser., vol. iv, sec. iv, p. 133, pi. I, figs. 2 a-c. 



