barton: a new genus of the cheiruridae. 555 



cephalic border. From Ccraurinus icarus (Billings) it may be distin- 

 guished by the more complete separation of the basal lobes of the 

 former, and from Chcirurus pompilius Billings by the more rectangu- 

 lar form of the basal lobes of the latter. 



Formation and Locality. — Lower Trenton at Minneapolis, Minn., 

 the Glades, Lebanon, Tenn.; Black River at Newport, N. Y. The 

 specimen figured (M. C. Z. No. 13), is from the latter locality, and was 

 collected by Dr. C. D. Walcott. 



Ceraurinus confluens, sp. nov. 



Plate, fig. 3. 



This trilobite is known only from two fragmentary specimens of the 

 cephalon. The general outline of the cephalon is semicircular. The 

 glabella is, in width, about one third of the extreme width of the 

 cephalon, is strikingly rectangular, but with rounded corners, a slightly 

 rounded and a slightly concave posterior, and is moderately convex. 

 The glabellar furrows are linear with sharply rounded edges, are 

 about one third of the width of the glabella in length, and slope 

 gently backward. The two anterior pairs of glabellar furrows open 

 cleanly into dorsal furrows. The posterior pair, however, fail to cross 

 the outer edge of the glabella, and at each end are separated from the 

 dorsal furrow b}^ about one sixteenth of the glabella. The eye is situ- 

 ated in the middle of the cheek and about opposite the second glabellar 

 furrow. The posterior portion of the facial suture, running outward 

 from the posterior of the eye, curves slightly forward and apparently 

 cuts the margin about on a level with the eye. The anterior portion 

 of the suture runs forward from the eye bending slightly inward. 

 The glabella is smooth. The cheeks are perhaps faintly pitted. The 

 neck-furrow is narrow and moderately deep. Its course is similar to 

 those of the other members of the genus. 



Measurements. — Length of cephalon 23 mm. 



Half-width of cephalon 20 mm. 



Width of glabella 13 mm. 



Position of eye 



Ratio distance eye to posterior margin to length 



of cephalon . 43 



Ratio distance eye to glabella to length of 

 cephalon 0.21 



