DESCRIPTION OP GENERA AND SPECIES. 175 



scattered pustules. The cephakm of the type and only specimen in the collection 

 has a length of 4 mm. 



Formation and Locality. Middle Cambrian : (030) Layer in black oolite of the 

 Ch'ang-hia limestone [Blackwelder, 19070, p. 33 (part of first list of fossils)], 25 

 feet (7.5 m.) above the second cliff at an elevation of 1,700 feet (568.9 m.) on top of 

 the long north and south ridge at Ch'ang-hia, Shan-tung, China. 



Collected by Eliot Blackwelder. 



Menocephalus acis Walcott. 

 Plate 1 6, Figure n. 



Menocephalus acis WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxix, p. 60. (Species described as 

 below.) 



Glabella prominent, convex, narrowing slightly from its base toward the 

 broadly rounded front; occipital furrow narrow, deep, and separating a rather 

 strong, rounded occipital ring; dorsal furrow narrow and strongly defined. 



Fixed cheeks about one-half the width of the glabella, moderately convex to 

 the base of the palpebral lobe ; posteriorly they slope rapidly to the furrow within 

 the posterior margin, anteriorly rapidly to the frontal rim; palpebral lobe small 

 and somewhat elevated ; frontal rim narrow, rounded, and separated from the gla- 

 bella by the narrow dorsal furrow. 



Surface marked by rather strong, scattered granules. 



The only specimen representing this species has a length of 5 mm. 



This species is characterized by its narrow, wire-like frontal rim and the scat- 

 tered granules on its outer surface. 



Formation and Locality. Middle Cambrian: (C35) Upper part of the Ch'ang- 

 hia limestone [Blackwelder, igoya, p. 33, fifth paragraph], at Ch'au-mi-tien, Shan- 

 tung, China. 



Collected by Eliot Blackwelder. 



Menocephalus admeta Walcott. 

 I'kile 1 6, Figure 12. 



Men"' f filial it.-, ntlincta WALCOTT, HJO.S, Proc. U. S. Nat. Mus., vol. xxix, p. 61. (Described as a new 

 species as below.) 



Glabella strongly convex, with subparallel sides and rounded front; occipital 

 furrow narrow and deep; occipital ring narrow at the sides, increasing in width 

 toward the center, slightly convex, rising with a backward slope from the bottom 

 of the occipital groove; dorsal furrow narrow and strongly defined. 



Fixed cheeks about two-thirds of the width of the glabella, slightly convex oppo- 

 site the palpebral lobe, and sloping downward to a strong furrow within the rounded 

 rim of the short postero-lateral limb ; frontal rim narrow and slightly rounded. 



Surface with minute tubercles under a strong lens. 



The only cephalon of this species in the collection has a length of less than 2 mm. 



This species is distinguished from M. acis by the form of the convex glabella 

 and flattened instead of wire-like frontal rim. It does not appear to be closely 

 related to any other species. 



Formation and Locality. Middle Cambrian: (C22) Ch'ang-hia limestone, in 

 upper oolitic portion [Blackwelder, 190717, pp. 22 and 33 (part of last list of fossils)], 

 at Ch'ang-hia, Shan-tung, China. 



Collected by Eliot Blackwelder. 



