289 



furrows on each side extending one-third across ; anterior lobes equal to 

 half the whole glabella, and subdivided by two short oblique furrows 

 pointing inwards and backwards, situated half way between the median 

 line and the anterior angles, and near but not cutting the front margin ; a 

 third small pit in the middle of the front margin is visible in casts of the 

 interior. The eyes appear to be small and situated opposite the posterior 

 half of the second lobe, and a httle less than one-third of the length of the 

 head from the side of the glabella. 



Pygidium moderately convex, axis conical, convex, well defined, with 

 six segraents (the last one triangular terminating in an acute point, and 

 having a rudely semicircular pit just above the middle) ; side lobes with 

 five ribs on each side, all extending beyond the margin and terminating 

 in flattened pointed spines. The last two ribs are parallel with the axis ; 

 the next two diverge a little, but are still nearly parallel ; the three 

 anterior pairs diverge more widely, the anterior being at right angles to 

 the axis for about half the length, the outer half curved backwards. In 

 some specimens the anterior ribs are broadly curved, for the inner half. 

 The spinose terminations of the ribs are separated from each other about 

 the width of the rib. The length of the pygidium, measuring to the tips 

 of the spines, is a little more than half the width. 



The. surface appears to be finely tubercular. 



This species is closely allied to A. Lindaueri (Barrande),* which occurs 

 in rocks lying at the base of the second Fauna in Bohemia, but differs in 

 the form of the triangular or last segment of the axis, and in having the 

 ribs more divergent. It differs from A. Canadensis in having the ribs 

 more divergent, and in being less convex. f 



A. Salteri has three glabellar furrows on each side, but none in the front 

 margin. 



Locality and Formation. — I, K, L, Point Rich ; L, M, N, Table Head 

 and Bonne Bay ; P, Portland Creek and Cow Head, Newfoundland ; 

 Quebec group. 



Oollector. — J. Richardson. 



* (Bareande.) SysUme Silurun du centre de la Boheme, page 820, pi. xxx. 



f In j1. Canadensis, the last or triangular segment of the axis is minute in young 

 specimens, but becomes gradually larger and elongated as the individual increases in 

 size. 



