22 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxix. 



CEPHALOPODA. 



Genus CYRTOCERAS Goldfuss. 

 CYRTOCERAS CAMBRIA, new species. 



Shell gently curved, laterally compressed. Section ovate, dorso- 

 ventral diameter as compared with the lateral diameter toward the 

 last chamber being- nearly as four to three, the greatest lateral diame- 

 ter being nearer the dorsal than the ventral side; dorsal side more 

 obtusely rounded than the ventral. Septa arching slightly forward 

 from the dorsal side; short, about five in a distance of 2.5 mm. 

 where the shell has a diameter of from 1 to 1.5 mm. Chamber of 

 habitation supposed to be of moderate depth; none of the specimens 

 clearly show the margin of the aperture. 



This species is represented by a number of more or less fragmentary 

 specimens. The largest has a dorso-ventral diameter near the aper- 

 ture of 8 mm., with a length of 7 mm. to where the diameter is 1.25 

 mm. ; chamber of habitation appears to have a depth of 2 nmi. The 

 siphuncle in a specimen 2.25 mm. in the dorso-ventral diameter has a 

 diameter of less than 0.2 mm.; it is situated on the dorsal side, and 

 almost reaches the exterior surface of the thin shell, which is some- 

 what thickened on the dorsal side. 



This little shell appears to be a true Cyrtoceras. Occurring as it 

 does well down toward the base of the Chao Mi Tien limestone, the 

 fauna of which is of upper Cambrian age, makes it of great interest, 

 as it is the oldest known representative of the genus, and, unless Vol- 

 borthella is considered to be a cephalopod, is the oldest known 

 representative of that class. 



Formation and locality. — Upper Cambrian, lower portion of Chao 

 Mi Tien limestone; Pagoda Hill, 1 mile west-southwest of Tai An 

 Fu, Shangtung, China. 



Collected by Eliot Blackw elder, of the Carnegie Institution of 

 Washington Expedition to China. 



TRILOBITA. 



Genus AGNOSTUS Brongniart. 

 AGNOSTUS KUSANENSIS, new species. 



Cephalic shield moderately convex, a little wider than long, semi- 

 circular in outline, and slightly contracted at the posterior lateral 

 angles; the narrow, rim-like, rounded border is broadest at the front, 

 narrowing toward the postero-lateral angle, around which it curves, 

 and extends about one-fourth the distance across the posterior margin 

 of the head; dorsal furrow well defined on the sides, but rather faint 

 in front of the large posterior lobe of the glabella. 



