NO. 13 DIKELOCEPHALUS AND OTHER GENERA 391 



fine, raised irregular lines that occur on the glabella, fixed cheeks, 

 border of cephalon, thoracic segments, and central parts of the 

 pygidium. 



The species is clearly separated by its occipital spine from Saukia 

 leucosia (pi. Gy, figs. 14, 16), the form nearest to it, and by the asso- 

 ciated pygidia (Compare dififerences in figs. 18, 19, pi. 68, with figs. 

 17, 17a, pi. 67). 



The pygidium recalls some of the pygidia referred to Anomocare 

 from the Middle Cambrian of China.^ 



Formation and locality. — Upper Cambrian : St. Lawrence forma- 

 tion ; (83*, 83^ 135c, and i35d), Trempealeau, Trempealeau County, 

 Wisconsin (Chas. Schuchert, 1893). 



Locality 83^ is above the Dikelocephalus minnesotensis zone of 83" 

 (= 135c and i35d). 



CALVINELLA TENUISCULPTA, new species 



Plate 64, figs. 7, 7a 



This species is represented by a single cranidium that in propor- 

 tions and most details approaches quite closely the cranidium of 

 Calvinella spiniger (pi. 68). It differs in having a more convex 

 border and slightly broader fixed cheeks in front of the palpebral 

 lobes. 



The test appears to be minutely punctate and to have obscure, irre- 

 gularly arranged, fine flat ridges crossing and curving forward on the 

 glabella. 



The type specimen of the cranidium has a length of 1 1 mm. 



Formation and locality .—hower Ordovician ( ? Ozarkian) : (201a) 

 Pogonip limestone ; east slope of the ridge east of Hamburg Ridge, 

 Eureka district, Nevada (C. D. Walcott, 1882). 



^ Research in China, Vol. 3, Carnegie Institution of Washington, Pub. No. 

 54, 1913, The Cambrian Faunas of China, pi. 18, figs, lb, 4c. 



^ Dikelocephalus, species undetermined. Fragments of a large species of 

 Dikelocephalus occur in collections from the Gallatin limestone on the west 

 side of the Bridger Range, Gallatin County, Montana (locality 151, Upper 

 Cambrian). The glabella of the cranidium is similar to that of D. minneso- 

 tensis and the associated pygidium appears to be similar to that of D. ? lim- 

 batus. (This note was added after the present paper was in page proof.) 



