298 







the posterior furrow. The anterior lobes of the axis are distinctly sepa- 

 rated from the tubercle by a narrow groove ; the second two are not. 



Surface apparently smooth, but in one of the specimens there are indi- 

 cations of small wrinkles which unite with each other so as to give a reti- 

 culated aspect, somewhat similar to that of A. reticulatus (Angelin). 



Length of head and pygidium from 1 to 2 lines each. 



This species is allied to A. Americanus, but has the axis of the pygidium 

 shorter, and no tubercles on the head. 



A. gldbratus (Angelin) has two short spines on the posterior angles of 

 the pygidium, but in all other respects resembles this species very closely. 



A. tardus (Barrande) is also very closely allied to this species, differ- 

 ing only in the shorter axis of the pygidium, and in having the tubercle of 

 an uniform height its whole length. 



Locality and Formation. M, and N, Table Head and Pistolet Bay; 

 P, four miles N. E. from Portland Creek, Newfoundland ; Quebec group. 



Collector. J. Richardson. 



AGNOSTUS FABIUS. (N. sp.) 



Fig. 289. 



Description. Head uniformly and moderately convex, semi-elliptical, 

 front margin broadly rounded ; a very narrow, flat rim all round the front 

 and sides ; glabella a little more than one-third the whole width, scarcely 

 at all elevated above the general surface, not defined in front, and only 

 obscurely so in the posterior half, by the dorsal furrows, which are parallel 

 and become obsolete about the middle of the head. On each side of the 

 glabella, at the posterior margin, there is, in the dorsal furrow, a small 

 triangular lobe. 



The pygidium is proportionally a little more elongated than the head ; 

 posterior margin uniformly rounded ; a narrow, flat rim all round to the 

 anterior angles. The axis is a little more than one-third the whole width, 

 about one-fourth narrower at the apex than at the front margin ; the apex 

 rounded, or with a portion in the middle somewhat straight ; sides nearly 

 straight, well defined by the dorsal furrows ; two pairs of transverse 

 furrows, the posterior reaching the median line, where there is a small 

 rounded tubercle, situated a little behind the mid-length (of the axis) ; 

 the anterior furrows half way between the tubercle and the front margin, 

 their position, however, slightly variable ; their inner extremities sepa- 

 rated by about one-third the width of the axis. Surface apparently 

 smooth. 



Length of the largest head seen, about 2 lines ; length of the largest 

 pygidium observed, about Ij lines. 



