NO. 3 CAMBRIAN TRILOBITES 217 



CREPICEPHALUS TUMIDUS, new species 

 Plate 31, fig. 2 



This species is represented by cranidia. It differs from the cra- 

 nidia of the most nearly related species, C. texanus and C. thoosa, 

 by greater convexity of glabella and more strongly tuberculated 

 surface. Test apparently punctate. The largest cranidium has a 

 length of 25 mm. 



It is unfortunate that we have only the cranidia of this fine species, 

 but as they are closely allied to the cranidia of C. texanus, it is highly 

 probable that the entire dorsal shield of the two forms was essen- 

 tially similar. 



Formation and locality. — Upper Cambrian: (120) Maryville 

 limestone ; north of Bays Mountain, on Beaver Creek, Sevier County, 

 18 miles (28.8 km.) east-northeast of Knoxville, Tennessee. 



CREPICEPHALUS UNCA, new species 

 Plate 35, figs. I, la-e 



The pygidium of this species is not unlike that of C dis (pi. 32, 

 fig. i) from the House Range of Utah. It differs in having the two 

 posterior spines of the pygidium near together and in their broader 

 base where joining the flattened border. 



The associated cranidium is similar in outline to that of C. dis, 

 but differs in having proportionally broader fixed cheeks. 



The largest pygidium has a length of 12 mm. exclusive of the 

 spines. 



Formation and locality. — Upper Cambrian: (yge) Eau Claire 

 formation; Willow River Falls, near Hudson; (79) Hudson, St. 

 Croix County, Wisconsin. 



CREPICEPHALUS UNZIA, new species 



Plate 34, figs. 7, 7a 



This species, like C. unca, is related to C. dis (pi. 32, fig. ib) and 

 C. augiista (pi. 29, fig. 6h) by the form of the pygidium, but the 

 backward-extending spines are not attachments to the border, as 

 the furrows indicating the anchylosed segments extend back onto 

 the base of the spines as shown by figure ya. The cranidium is quite 

 unlike that of C. dis. It has a concave frontal rim and border that 

 give it a very distinct appearance. 



Surface slightly pitted and test apparently punctate. The largest 

 cranidium has a length of 7.5 mm. 



