48 NEW YORK STATE MUSEUM 



McCoy 1 . A comparison of the description and figure with our 

 spcecimen shows a close similarity in the two forms, the limb 

 in both being apparently alike, even to the breaking up of the 

 radial rows into irregular arrangement at the lateral angles. The 

 principal difference between the two species seems to lie in the 

 •shape of the glabella, which in the Trenton form is highly con- 

 vex, with a hemispheric frontal part and an abrupt contraction 

 to a narrow ridge behind the same, as in T . reticulata. 



The posterior part of the glabella and cheeks are not so well 

 •preserved as indicated by the drawing. 



am pyx Dalman 



Subgenus lonchodomas Angelin 



Ampyx (Lonchodomas) hastatus sp* no<v. 



PI. 3, fig. 1-10, 30 



The black compact limestone pebbles contain in great abun- 

 dance cranidia and pygidia of a new species of Ampyx in 

 association with such Trenton fossils as P t erygometopus 

 <c a 1 1 i c e p h a 1 u s . 



Diagnosis. Cranidium hastate in appearance, terminal points 

 of glabella and fixed cheeks falling approximately into the angles 

 oif a regular triangle. Glabella subrhombic, contracted ante- 

 riorly and posteriorly, most convex and widest near the middle; 

 more than half of it projecting snoutlike from the remainder of 

 the cranidium; carina (or in others only a flattened area) extend- 

 ing the whole length of the glabella. Two long elliptic depres- 

 sions, beginning in the pits at the base of the glabella, directly 

 in front of the neck furrow, extend at the foot of either slope 

 of the glabella for about one fourth of its length; two others 

 directed obliquely downward, lie at the anterior end's of the 

 dorsal furrows at the point where glabella and fixed cheeks meet 

 exteriorly; two more lie directly above the others and are par- 

 allel to the axis of the glabella. On casts of the glabella (pi. 3 

 fig. 7) two prominent, transversely elliptic elevations! can be 

 noticed directly in front of the neck ring. On the crust they 



i Syn. of classif. of Brit. pal. foss. 1855. pi. 1 E, fig. 16. 



