LOWER HELDERBERG ROCKS. 351 



Surface marked by undulating laraellose strife, which are arched upwards 

 on the ribs : intermediate spaces covered by fine granulations. 



This species is closely related to the B. partschi and B. nuntiusoi Barkande; 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. tiuntius, 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 east of the impression in stone.) 



Fig. 2. The inipres.sion of the same. 



Fig. 3. Profile of the same. 



Fig. 4. Enlargement of the surface, showing the undulating striae and minute granulations. 



Geological fosition and locality. In the pentamerus limestone of the Lower Hel- 

 derberg group : Schoharie county. 



Proetus ])i'utul»erans ( n. s ). 



Plate LXXIII. Fio. 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. 



Pygidiom semicircular ; axis very prominent, marked (in the cast) by 

 eight annulations ; lateral lobes marked by four or five ribs. 



Surface granulate ; the anterior border, and articulating surfaces of the 

 axis, striate : exfoliatad surfaces striate. 



This species bears some resemblance to P. hohemicus of Barrande, but is pro- 

 portionally narrower and the head is smaller. The specimens observed are a single 



