782 CAMBEIAN BRACHIOPODA. 



the character of the surface more fully than the illustrations given oy Matthew [1892, PL XII, 

 figs. 13a-c]. As far as known, the characters of the shell are those of the group of species 

 referred to Eoorthis. 



Formation and localitt.— TJpper Cambrian: (308b [Matthew, 1892, p. 49]) Limestone lentiles in black shales 

 of Division C3a of Matthew's section, Germaine Street, St. John, St. John County, New Brunswick. 



Eoorthis katseei (Walcott). 



Plate XCVII, figures 6, 6a-b. 



Orthis (Plectorthis) hayseri Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28, p. 266. (Characterized as below as a new 

 species.) 



This is a larger shell than Eoorthis linnarssoni (Kayser), with which it is associated. Its 

 surface is marked by numerous fine radiating strise, four or five in a distance of 1 millimeter, 

 and the inner layers of the shell appear to be minutely punctate. The ventral valve is more 

 convex than the dorsal, the latter being nearly flat in young shells. Nothing is known of- 

 the interior, except one cast of the pseudospondylium of the dorsal valve, which is larger in 

 proportion than that of E. linnarssoni. 



The largest ventral valve has a length of 14 mm.; width, 20 mm. 



This species belongs in the group of Eoorthis represented by E. desmopleura (Meek) and 

 E. linnarssoni (Kayser). 



The specific name was given in honor of Dr. E. Kayser. 



FoEMATiON AND LOCALITY. — Upper Cambrian: (C64:) Upper limestone member of the Kiulung group [Blachwelder, 

 1907a, pp. 37 and 42 (first list of fossils), and fig. 10 {bed 20), p. 38], 2.7 miles (4.3 km.) southwest of Yenchuang, Sintai 

 district, Shantung; (C68) upper part of the Chaumitien limestone [Blackwelder, 1907a, p. 36 (part of third list of 

 fossils)], at Chaumitien, Changhia district, Shantung; and (C74) a dense blue dolomitic limestone at the top of 

 the Kic'hou limestones [Willis and Blackwelder, 1907, pp. 139 and 145 (5th list of fossils)], 4 mUes (6.4 km.) east of 

 Fanglanchon, Shansi; all in China. 



Eoorthis kichouensis (Walcott). 

 Plate LXXXIX, figure 5. 



Orthis (Plectorthis) kichouensis Walcott, 1906, Proc. U. S. Nat. Mus., vol. 30, p. 570. (Described as below as a new 

 species.) 



This species is represented by one specimen of the dorsal valve. The outline of the shell 

 is transversely rounded subquadrilateral; length, 9 mm.; width, 13 mm.; the highest point 

 above the plane of the margin is about 3 mm. ; the shallow median sinus, which begins at the 

 umbo above the hinge line, gradually widens toward the front margin; the umbo curves over 

 beyond the hinge line and then under to the beak, which apparently is at or a little over the 

 upper edge of a very narrow area. 



Surface marked by numerous radiating, rounded ribs, with narrow interspaces, 7 ribs in a 

 distance of 45 mm.; a few bifurcations of the ribs occur at irregular intervals between the 

 apex and the margins. There are no traces of concentric stri^; if on the shell originally, they 

 have been removed by the wearing off of the outer surface. 



Ohservations. — This species is distinguished from all other species by the strong, incurved 

 umbo and rounded ribs with narrow interspaces. 



The specific name was derived from the Kichou formation, in wliich the species occurs. 

 Formation and locality. — Middle Cambrian: (C75) Limestone near the base of Kichou formation [Willis and 

 Blackwelder, 1907, p. 143], 4.5 miles (7.2 km.) south of Wutaihien, Shansi, China. 



Eoorthis linnarssoni (Kayser). 



Plate XCVII, figures 5 and 5a. 



Orthis linnarssoni Kayser, 1883, China, by Richthofen, vol. 4, p. 34, PI. Ill, fig. 1. (Described and discussed in 

 German as a new species, see p. 783 for translation. Fig. 1 is reproduced in this monograph, PI. XCVII, fig. 5a.) 



