LOWER HELDERBERG ROCKS. 
351 
Surface marked by undulating lamellose strise, which are arched upwards 
on the ribs : intermediate spaces covered by fine granulations. 
This species is closely related to the B. partschi and B. nuntius of Barrande; but 
the pygidium being the only part of our species which has been seen, a satisfactory 
comparison cannot be made. The surface marking, however, though more nearly 
resembling that of B. nuntius , is different from that of either of the Bohemian 
species. 
Fig. 1. The pygidium of the natural size. (The specimen is imperfect, and the figure is com¬ 
pleted from a cast of the impression in stone.) 
Fig. 2. The impression of the same. 
Fig. 3. Profile of the same. 
Fig. 4. Enlargement of the surface, showing the undulating striae and minute granulations. 
Geological position and locality. In the pentamerus limestone of the Lower Hel- 
derberg group : Schoharie county. 
Proetus protufoerans (n. s.). 
Plate LXXIII. Fig. 5, 6, 7, 8. 
Entire form oblong elliptical. Head semicircular, very gibbous ; the gla¬ 
bella very prominent, rounded in front, not distinctly lobed ; the cheeks 
sloping abruptly from the eyes to the outer margin : posterior angles 
subacute (perhaps prolonged into spines in entire specimens); eyes 
prominent. Occipital annulation prominent; the furrow strong, and 
marked below each posterior angle of the glabella by a small tubercle. 
Thorax consisting of nine or ten articulations (the specimen being too 
imperfect for actual determination). The axis is very prominent, semi- 
cylindrical, and the lateral lobes nearly flat for a little distance from 
their origin, and then bending abruptly downwards. 
Pygidium semicircular : axis very prominent, marked (in the cast) by 
eight annulations; lateral lobes marked by four or five ribs. ~j~ 
Surface granulate; the anterior border, and articulating surfaces of the 
axis, striate : exfoliated surfaces striate. 
This species bears some resemblance to P. bohemicus of Barrande, but is pro¬ 
portionally narrower and the head is smaller. The specimens observed are a single 
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