DESCRIPTION OF GENERA AND SPECIES. 143 



Genus LONCHOCEPHALUS Owen. 



Lonchocephalus tellus (Walcott). 



Plate 14, Figure i. 



Ptychoparia tellus WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxix, p. 80. (Described as a new 

 species essentially as below.) 



All that is known of this species is the central part of the cephalon, exclusive 

 of the free cheeks. The specimens occur on the surface of shaly limestone, and are 

 probably somewhat compressed; their convexity is relatively slight. Glabella 

 large, convex, and nearly as wide in front as at the base; three pairs of glabellar 

 furrows are indicated on the somewhat eroded outer surface of two specimens; 

 occipital furrow shallow, narrow, and rounded, but quite distinct; occipital ring 

 narrow at the sides, increasing in width and inclining backward toward the middle, 

 where it rises to the base of a strong spine, which is directed upward and backward ; 

 the spine is nearly straight, and about as long as the length of the head; dorsal 

 furrow clearly defined on the sides and in front of the glabella. 



Fixed cheeks slightly convex and less than half the width of the glabella; 

 palpebral lobes rather large; palpebral ridges clearly denned and merging into the 

 palpebral lobes; frontal limb short, slightly convex, and merging into the flattened 

 frontal rim, the line of demarcation between the two being very slight; postero- 

 lateral limbs small and short. 



Surface unknown. 



The largest cephalon in the collection has a length of 10 mm., with a width of 

 ii mm. at the outer edges of the palpebral lobes. 



This species is most nearly related to Lonchocephahts hamulus Owen [1852, 

 p. 576]. It differs in having wider fixed cheeks and in the proportion of length of 

 the frontal limb and rim as compared with the glabella. 



Formation and Locality. Middle Cambrian : ((_! 2) Lower shale member of the 

 Kiu-lung group [Blackwelder, 19070, pp. 37 and 40 (part of the third list of fossils), 

 and fig. 10 (bed 4 and 5), p. 38], 2 miles (3.2 km.) south of Yen-chuang, Sin-t'ai 

 district, Shan-tung, China. 



Collected by Eliot Blackwelder. 



Genus LIOSTRACINA Monke. 



Lioslracina MONKE, 1903, Jahrb. konigl. preuss. Geol. Landesanstalt und Bergakademie, vol. xxim 

 pt. i, p. 114. 



The generic name Liostracina simply precedes the name and description of the 

 type species L. krausei Monke. 



Liostracina krausei Monke. 

 Plate n. Figure 8; Plate 14, Figures 2, 20.. 



Lioslracina krausei MONKE, 1903, Jahrb. konigl. preuss. Geol. Landesanstalt und Bergakademie, vol. 



xxni, pt. i, p. 1 14, plate 3, figs. 10-17. (Species described and discussed.) 

 Ptychoparia ecus WALCOTT, 1905, Proc. U. S. Nat. Mus., vol. xxix, p. 76. (Described as a new species 



essentially as below.) 



Cephalon, exclusive of free cheeks, transversely subrhomboidal in outline, broadly 

 rounded in front, convex. Glabella conical, moderately convex, and marked by 

 two pairs of short, shallow furrows that extend in but a short distance on the sides; 

 occipital furrow rounded, very distinct, and continued outward on the postero- 

 lateral limbs, where it is stronger and deeper; occipital ring narrow at the sides, 



