CAMBRIAN FAUNAS OF CHINA— WALCOTT. 59 



furrows are shown l>y reiiected light; occipital furrow a faint trans- 

 verse depression that se])arates the olabella from a fairl}^ strong-, 

 slightly convex occipital ring; dorsal furrow narrow hut clearly 

 defined. 



Fixed cheeks very narrow and sloping away from the gla])ella 

 toward the palpebral lobes; posteriorly they slope downward into a 

 rather large postero-lateral limb; anteriorly they slope rapidly to the 

 frontal limb; palpebral lobes prominent, about one-fourth the length 

 of the head; frontal limb gently convex, rounded in front, and with- 

 out traces of a frontal rim. 



Surface smooth under a strong lens. The type specimen has a 

 length of 4 mm. 



In form the head of this species is somewhat like that of A. alala. 

 It differs in the absence of an occipital spine and in being proportion- 

 ately somewhat narrower. 



Fcmnat ion and local! ty.—M\di&\Q, Cambrian, central portion of. the 

 Chang Hsia formation, in gray crystalline limestone; 3.25 miles south- 

 west of Yen Chuang, Hsin Tai, Shangtung, China. 



Collected by Eliot Blackwelder, of the Carnegie Institution of 

 Washington Expedition to China. 



ARIONELLUS ALALA, new species. 



In general form and proportion the central parts of the head of this 

 species are much like A. agonius. They differ in the proportionately 

 smaller, elongate glabella, nearly flat frontal limb, and a thin instead 

 of a rounded margin. 



Fonnation and locality. — Middle Cambrian, central portion of the 

 Chang Hsia formation, in gray limestone; Chao Mi Tien, Shangtung, 

 China. 



A somewhat similar and possibly identical form occurs at about the 

 same horizon near Yen Chuang, Hsin Tai, Shangtung, China. 



Collected by Eliot Blackwelder, of the Carnegie Institution of 

 Washington Expedition to China. 



Genus MENOCEPH ALUS Owen. 

 Menocvphalus Owen, Geol. Surv. Wisconsin, Iowa, and Minnesota, 1852, p. 577. 



Doctor Owen proposed this genus for trilobites having a highly 

 convex, hemispherical glabella, with a narrow border and a broadly 

 rounded front; cheeks tumid. 



I have referred to this genus, more or less provisionals, several 

 species in which only the central portions of the head are pre- 

 served. Further study, or the stud}^ of more perfect specimens, will 

 undoubtedly lead to the reference of some of them to other genera. 



