On the (renHy Auij>;/.r. — Vogde--^. 107 
dorsul furrows or just iu the iingle formed hy the junction of the 
base of the glabella with the fixed cheeks. The neck segment is 
a flat plate inclining ui)\vards and l»ack\vai"ds at an angle of about 
45 degrees. The neck furrow is well defined all across the whole 
width of the head, l)eing least distinct in passing over the pos- 
terior part of the glabella. Pygidium semi-oval with a flat 
border all round al>ruj)tly bent down at nearly a right angle. 
Axis conical, moderately con\ex extending the whole length and 
causing a slight i)rojection in the posterior margin. Side lobes 
nearly flat, with .j or (i flat ril)s. each witji a fine pleural grove 
extending the whole length. On the axis 10 or \'l clo.sel}- 
crowded annulations occupying o-li the lengths: the apex being 
apparently smooth. Length of the head excluding the spine ?>k 
lines measui-ed along the base of the glabella. 
Geolor/iral position. — Chazy, St. l>oininifnie, Canada East, and at 
Highgate Springs. Vermont. 
Fig. 6. A. se'imcostatm' Bill. A. nornxiHs Bill. A.beimtsriilnx Bill. 
AMPYX NORMALIS Hillings, lS6o. 
Compare Anqjiir hcrutscuhix Billings. i<c .1. rostrntua Sars. 
Diagnosis. — Head, without the movable cheeks, triangular, 
the width about ^ greater than the length; fixed cheeks gently 
convex, smooth: neck segment consisting ot a flat i)late inclining 
backwards. The glabella elongate-oval, greatest width about 
mid-length, j narrower at the neck segment, the apex extending 
a little over the front margin of the head: the spine apparently 
equal to the whole length of the head, not rounded but fluted, a 
characteristic of the spine of Anipi/x ms/rnfus. Tliere are 2 or 
3 ovate or nearly circular scars, one on each side of the itlabella 
in the posterior half. 
or the two i)ygidia deserilied from 'I'alile Head liy Hillings 
u ider the names of Aiiipi/x hi oiitscn/ns and .1. tioniniUs. I think 
that the pygidium of .4. Ifirinscnlns siioidd be connected with the 
