181 



ing about one-third across ; neck segment narrow ; neck furrow extend- 

 ing all across. 



Length and width of largest specimen seen, 4 lines. 



This species is only known by detached glabellse, and these so closely 

 resemble S. mirus (Beyrich) that I have some doubts as to whether they 

 should receive a new name. Forms very similar occur in the Quebec group. 



Locality and Formation. Island of Montreal ; Chazy limestone : also, 

 south side of Large Island, Mingan Islands ; Chazy, or Black River. 



Collectors. J. Richardson, E. Billings. 



CHEIBUBUS POMPILIUS. (N. sp.) 



Fig. 162. 



Description. Of this species only the glabella, with portions of the 

 fixed cheeks attached, and the neck segment broken off, has been found. 

 The glabella is rectangular; sides straight and parallel; front gently 

 convex, with a very narrow marginal rim. There are three pairs of gla- 

 bellar furrows, all extending about one-third across and inclining a little 

 backwards. The posterior lobes are isolated. The anterior lobes occupy 

 nearly two-fifths the length of the glabella, and the others about one-fifth 

 each. The cheeks are punctured. The glabella is only moderately convex, 

 not abruptly elevated in front. 



Length of the glabella, without the neck segment, about 7 lines ; width 

 6 lines. 



Locality and Formation. South side of Large Island, Mingan Islands ; 

 Chazy, or Black River. 



Collector. J. Richardson. 



LlCHAS MlNGANENSIS. (N. Sp.) 

 Fig. 163. a, &. 



Descriptiovi. Head very convex, abruptly tumid in front ; width of 

 the middle lobe, at the neck furrow, about two-fifths the whole length of 

 the head, exclusive of the neck segment ; the furrows on each side of said 

 lobe nearly parallel for about half the length, then curving outwards so as 

 to make the width of the lobe in front equal to the length. The side lobes 

 are of a reniform shape, truncated behind by the neck furrow, about two- 

 thirds the length of the head, and in their greatest width about equal to 

 the width of the median lobe in its posterior half. Length of the largest 

 specimen, exclusive of the neck segment, eight lines. Surface with 

 numerous rounded tubercles, the largest of which are about half a line in 

 diameter. 



