178 RESEARCH IN CHINA. 



The length of the glabella and frontal rim is 2.5 mm. in one specimen, with an 

 occipital ring about i mm. long. 



The above is all that is known of this form. Its globose glabella, convex fixed 

 cheeks, and occipital ring distinguish it from other species and at the same time 

 bring it close to Levisia agenor. What I considered to be fine granules on the surface 

 when describing the species in 1905, I now recognize as the irregular ridges about 

 the shallow pits. 



Formation and Locality. Middle Cambrian: (C30) 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. 



Levisia agenor (Walcott). 



Plate 14, Figure 19. 



Agraulos agenor WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxix, p. 44. (Species described essen- 

 tially as below.) 



Levisia agenor (Walcott), 191 r, Smithsonian Misc. Coll., vol. 57, p. 86, pi. 15, fig. 7. (Referred 

 and figured as genotype of new genus Levisia.) 



Glabella slightly truncato-conical, strongly convex; occipital furrow rounded, 

 clearly defined; occipital ring slightly convex, subtriangular in outline, narrow at 

 the sides, and broadening out to an obtuse spine behind; dorsal furrow narrow and 

 clearly defined. 



Fixed cheeks about one-half the width of the glabella, convex, rising from the 

 dorsal furrow and arching down to a small palpebral lobe; the fixed cheeks slope 

 rapidly backward to a short postero-lateral limb, and anteriorly to a rather broad, 

 very slightly convex frontal limb; a rather deep, narrow furrow occurs within the 

 elevated margin of the postero-lateral limb. 



Surface minutely pitted under a strong magnifier; the shallow pits are formed 

 apparently by an irregular network of elevated lines. 



The only specimen of the cephalon representing this species is 2.5 mm. long. 



Formation and Locality. Middle Cambrian: (C25) Limestone about 50 feet 

 (15 m.) below the Ku-shan shale in the uppermost beds of the Ch'ang-hia formation 

 [Blackwelder, 19070, p. 33 (part of the last list of fossils)], at Ch'ang-hia, Shan-tung, 

 China. 



Collected by Eliot Blackwelder. 



Levisia nasuta Walcott. 



Levisia nasuta WALCOTT, 1911, Smithsonian Misc. Coll., vol. 57, No. 4, p. 87, plate 17, fig. 5, and 

 text-figs. 7 and 70, p. 87. (Described and discussed as a new species.) 



Two Canadian species referred to this genus are found in association, Levisia 

 nasuta and L. richardsoni. The glabella of L. nasuta is very convex; fixed cheeks 

 narrow and merging anteriorly into the bluntly pointed frontal limb and margin. 

 A front and a side view of the specimen are represented on plate 17, Walcott, 1911. 

 Formation and Locality. Upper Cambrian conglomerate, at Point Levis, 

 Quebec. 



Levisia richardsoni Walcott. 



Levisia richardsoni WALCOTT, 1911, Smithsonian Misc. Coll., vol. 57, No. 4, p. 86, plate 17, figs. 4 and 

 40. (Described and discussed as a new species essentially as below.) 



The species associated with L. nasuta occurs with the same Upper Cambrian 

 fauna in the bowlders of the conglomerate at Point Levis, opposite Quebec, Canada. 

 To this species I have given the name of Levisia richardsoni in recognition of the fine 

 collecting work done by Mr. J. Richardson under the direction of Sir William E- 

 Logan. 



