414 



nearly straight or gently convex, neck furrow well defined all across, and 

 continued on the cheeks to the outer angles of the head, four lobes on each 

 side of which the anterior is largest, the posterior smallest, and the other 

 two almost equal to each other, the furrows directed obliquely forwards at 

 an angle of about 30, to the longitudinal axis, their inner extremities 

 distant from each other a little less than one-third the width of the glabella. 

 Cheeks moderately convex, punctured. Eye opposite the second lobe from 

 the front, and distant from the glabella apparently about the width of the 

 lobe. 



Length of head nearly four lines ; of glabella, about three lines and a 

 half ; width of glabella two lines and a half. 



Limestone, No. 2. 



Closely allied to a small species which occurs in the Chazy limestone at 

 Caughnawaga. Another of the same size and type occurs at Phillipsburgh. 



ASAPHUS ILLAENOIDES. (N. sp.) 



Description. Head very convex, in shape like that of an Illaenus, 

 equal to about one-fourth of a sphere, posterior angles rounded ; width a 

 little less than twice the length. Glabella obscurely defined, oblong, 

 slightly narrowed just behind the eyes, thence a little widened both for- 

 wards and backwards. Eyes sub-globular, of a medium size, close to the 

 glabella, the distance between their centres about equal to the length of 

 the head. The facial suture runs from the inner anterior angle of the 

 eye, with a scarcely perceptible curve outwards, directly forward to the 

 front margin, being in this part almost parallel with the longitudinal axis 

 of the body. From the inner posterior angle it runs outwards and back- 

 wards, and cuts the margin at a point in a line drawn parallel with the 

 axis of the body, passing outside of the eye at a distance therefrom equal 

 to one-half the width of that organ. The cheeks from the eye to the pos- 

 terior angle of the head, descend with a flat slope of about 45 to the hori- 

 zontal plane of the body. The surface appears to be smooth. 



The pygidium is depressed, convex, semicircular, the posterior margin 

 regularly rounded ; the axis depressed, semi-cylindrical, sub-conical, sides 

 a little concave, rather prominent, the extremity very obtusely round, the 

 length varying from a little more than one-half to two-thirds the total 

 length ; its width a little less than that of the side lobes, five very obscure 

 segments, of which the last two are sometimes blended into one. The an- 

 terior margins of the side lobes are almost at right angles to the axis for 

 one-half or thereabouts of the width, then sloping backwards to the outer 

 corners, which they reach at an angle of about 30 to the transverse dia- 

 meter of the body. 



