Branson — The Fauna of the Residuary Auburn Chert. 47 



pygidiiim; segments about nineteen, posterior ones indis- 

 tinct. Dorsal furrows concave inward. 



Pterygometopus lincolnensis 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. intermedins 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 INTERMEDTUS AValcott. 



PL vii. 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. 



PI. vii. 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 



