New Species of Trilobites. 371 



Dedicated to the discoverer Admiral Bayfield. 



Locality and formation. Trilobite Bay Mingan Islands, Chazy. 



Collectors. Sir W. E. Logan, J. Richardson. 



Ill^enus Americanus. (N. s.) 



Description. — Oblong, distinctly trilobed, length, two or three 

 inches; width about three-fifths the length ; proportional lenath 

 of head, thorax, and pygidium, as 12, 9, 8. 



Head large, transversely oblong or sub-oval, length two-thirds 

 the width, convex most prominent in the centre, behind strongly 

 trilobed by wide and deep dorsal furrows, which, towards 

 their anterior extremities have a sigmoid curve inwards and 

 outwards. Front margin somewhat straight or gently convex ■ 

 posterior margin straight as far as eye and then gently curved 

 forwards and outwards to the broadly rounded genal angle which 

 is situated in the front half of the lateral border. The eye is 

 not well preserved in our specimens, but enough remains to show 

 that it is not more than two lines in length in a large individual, 

 and situated rather more than half its length from the maro-in ; it 

 appears to be prominent, and is situated at a distance from the dor- 

 sal furrow equal to half the width of the axis. The facial suture 

 reaches the front margin a little within the parallel of the eye ; 

 behind the eye its course cannot be ascertained from our speci- 

 mens. 



Thorax of ten segments ; axis a little more than one third the 

 width of the whole animal, moderately convex, when not distorted 

 about one-fourth longer than wide, about one-ninth wider at the 

 first than at the last segment, sides nearly straight. 



On each side of the axis there is a flat space between the dor- 

 sal furrow and the bend of the pleurae ; the width of this space is 

 rather more than one-third the width of the axis. The pleurae 

 are bent at the fulcra at an angle of 45° and at a little more 

 than one-third their length from the side of the axis. 



The pygidium is comparatively small, its length being only 

 two-thirds that of the head, it is largely truncated at the ends, the 

 two lateral margins thus formed being straight and in length 

 nearly half the length of the whole pygidium ; the width of the 

 pygidium is twice its length. The dorsal furrows are strong at 

 the margin but die out at less than one-third the length, and the 

 axis is therefore not defined all round. 



The surface is remarkable. On the head it is thickly covered 



