94 RESEARCH IN CHINA. 
Hyolithes delia Walcott. 
Plate 5, Figure 18. 
Hyolithes delia WaLcoTt, 1905, Proc. U. S. Nat. Mus., vol. xxrx, p. 18. (Described and discussed as 
a new species essentially as below.) 
This species is represented by the dorsal side of a single specimen. It resembles 
the dorsal side of Hyolithes billingsi Walcott [1886, p. 134, plate 13, figs. 1b, re]. 
The dorsal surface is gently convex and is marked on each side, parallel to and a 
little distance within the margin, by a very shallow groove which outlines a central, 
more slightly convex area. The specimen is probably the interior cast. It shows 
a few forward-arching, concentric lines of growth. 
The type and only specimen representing the species has a length of 5 mm., 
with a width of 1 mm. at the smaller end and 2.25 mm. at the larger end. 
From the means of comparison afforded by the single specimen this species 
appears to be most closely related to Hyolithes billingsi. It differs in the more 
slender tube. 
Formation and Locality—lLower Cambrian: (C3) Lower part of the Man-t’o 
shale formation [Blackwelder, 1907a, p. 28 (list of fossils at bottom of page), and 
fig. 8a (bed 20 ), p. 38], on the southeast slope of Hu-lu-shan, 2.5 miles (4 km.) 
southwest of Yen-chuang, Sin-t’ai district, Shan-tung, China. 
Collected by Eliot Blackwelder. 
Hyolithes sp. undt. 
Plate 5, Figures 19, 20. 
This species is represented by a fragment of what appears to be the aperture 
of a species of Hyolithes, having a rather rapidly tapering tube. It is barely pos- 
sible that it is a crushed specimen of Orthotheca doris [plate 6, fig. 2]. 
Formation and Locality —Lower Cambrian: (C32’) A limestone bowlder col- 
lected in river drift 1 mile (1.6 km.) south of Chén-p’ing-hién, on the Nan-kiang 
River, southern Shen-si, China. 
Collected by Bailey Willis and Eliot Blackwelder. 
An operculum of unknown specific relations is illustrated by figure 20, plate 5. 
It is from Locality C4, Middle Cambrian, limestone nodules at the base of the lower 
shale member of the Kiu-lung group [Blackwelder, 1907a, pp. 37 and 40 (second list 
of fossils), and fig. 10 (bed 4), p. 38], 3 miles (4.8 km.) southwest of Yen-chuang, 
Sin-t’ai district, Shan-tung, China. 
Collected by Eliot Blackwelder. 
Genus ORTHOTHECA Novak. 
Orthotheca cyrene Walcott. 
Plate 5, Figures 21, 214. 
Orthotheca cyrene WALCOTT, 1905, Proc. U.S. Nat. Mus., vol. xxix, p.18. (Described and discussed as 
a new species essentially as below.) 
Form an elongate, slender, subtriangular tube, with the lateral margin rounded, 
tapering gradually from the base to an acute extremity. Transverse section 
rounded subtriangular, transverse and slightly concave toward the center on the 
dorsal side, rounded at the lateral angles, highly arched on the ventral side, with 
the ventral angle broadly rounded. Dorsal face of the lateral angles rounded, 
with a shallow depression, with rounded lateral slopes a little more than one-third 
the width of the face. Ventral face strongly and regularly convex transversely, 
