3GG 
PALAEONTOLOGY OF NEW-YORK. 
Fig. 6. Profile view of the same. 
Fig. 7. The hypostoma. 
Fig. 8. A part of the pygidium of this species. 
Geological position and locality. In tlie shaly limestone of the Lower Helderberg 
group : Coeymans, Schoharie and Carlisle. 
Lidias pustnlosus (n. s.). 
Plate LXXYII. Fig. 9 - 12; and Plate LXXVIII. Fig. 1-7. 
Head extremely ventricose : the limb is of moderate thickness, slightly 
recurved, leaving a comparatively broad shallow groove; margin of 
limb pustulose. The posterior margin of the head is moderately con¬ 
vex; the occipital furrow well defined, but not deep. 
The median lobe of the glabella is extravagantly elevated, standing out 
like a distinct protuberance in advance and above the interior lateral 
lobes : the form at the base is broadly ovate, gently narrowing behind 
for a little more than half its entire length to its greatest elevation, 
and, then abruptly declining and contracting, becoming almost flat 
between the anterior lateral lobes; showing a crest at the margin of 
the occipital furrow. The length and greatest breadth of this lobe are 
about equal, and the elevation from the frontal limb to the summit of 
the lobe is nearly equal to the width at the base in front. Anterior 
furrow shallow in front, becoming more defined in its posterior direc¬ 
tion, and, at the inward curving of the protuberant part of the median 
lobe, is very strongly defined, while in the posterior part it is scarcely 
below the plane of the central part of the median lobe. Anterior lobe 
oblong, narrow and depressed in front, gradually rising, spreading 
out and becoming protuberant behind. Entire surface pustulose; the 
pustules prominent, of various sizes, sometimes rising to the form of 
short spines. 
Two fragments, found in the same association, appear to be the movable 
cheeks of the species : the lower side only is visible, and the marking is 
similar to that on the lower side of the pygidium. 
