Branson—The Fauna of the Residuary Auburn Chert. 47 
pygidium ; segments about nineteen, posterior ones indis- 
tinct. Dorsal furrows concave inward. 
Pterygometopus lincolmensis differs from P. ebora- 
ceous in the absence of genal spines, in the third lobe of 
the glabella not being confluent with the second, in the 
absence of a tubercle on the occipital ring, in the frontal 
lobe of the glabella being shorter and broader, in the 
greater length and slenderness of the axis of the pygid- 
ium, in the longer eye, and smaller fixed cheek. 
It differs from P. intermedius in the shape of the first 
lateral furrow of the glabella, in the second lateral fur- 
row not reaching to the dorsal furrow, in the length of 
the eye, and the more strongly tuberculate character of 
the frontal lobe of the glabella. 
It differs from P. schmidti in the greater length of the 
cephalon, in the absence of tubercles on the free and fixed 
cheeks, in the shape of the anterior part of the cephalon, 
in the absence of genal spines, and in the confluence of 
the first and second lateral lobes of the glabella. 
Species based on several specimens of heads and 
pygidii, and one almost complete specimen. Numbers 
11484 11554 of the collection of invertebrate fossils of 
Walker Museum. 
PTERYGOMETROPUS INTERMEDIUS Walcott. 
Pl. vir. f. 20. 
The specimens referred to this species differ from the 
type and from those described by Clarke, in the genal 
spines reaching to the fifth or sixth thoracic segment and 
in the cephalon being nearly cresentiform. 
TECHNOPHORUS BELLISTRIATUS, N. Sp. 
Pl. vi. f. 21, 
Shell small, length fifteen millimeters, height nine mil- 
limeters, slightly higher anterior to beaks than posterior. 
Beaks situated about one-third the length of the shell 
from the anterior extremity, projecting about two milli- 
meters above the hinge plate. Posterior to the beaks the 
