770 CAMBEIAN BRACHIOPODA. 



Billingsella (Otusia) sandbergi (Wmchell), Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28, pp. 24&-247. (Described 

 and discussed essentially as in preceding reference, p. 769, and as below.) 



Shell small, transverse, subquadrate in outline, exclusive of the acute cardinal extremities. 

 Valves slightly convex, with a straight hinge line longer than the greatest width of the shell; 

 cardinal area narrow, but well developed on each valve and divided by a rather large open 

 delthyrium. 



The ventral valve slightly flattened at the cardinal extremities, rising toward the center 

 with a convex triangular swelling, broadening from the narrow beak to the front; beak small, 

 rounded, and extending slightly beyond the hinge line. Dorsal valve flattened at the cardinal 

 extremities, with well-marked rounded ridges rising between them, and a rather broad, well- 

 defined median sinus; beak very small, slightly encroaching upon the hinge line. 



Surface marked by fine, regular, radiating striae, between which one or more faint interme- 

 diate striae are sometimes visible ; under favorable conditions very fine concentric striae can be 

 seen, and there are also usually present more or less distinctly marked lines of growth. 



Very little is known of the interior of the ventral valve. Two fragments of the posterior 

 portion show a broad delthyrium, strong teeth, and a broad umbonal cavity opposite the 

 delthyrium. In the ventral valve the area is narrow and divided by a broad delthyrium, which 

 has a strong cardinal process that extends forward nearly three times the length of the area. 

 Anteriorly, it rests on a broad ridge that extends forward, gradually broadening out and disap- 

 pearing at the anterior margin of the shell. 



In my former description [1899, p. 453] I stated that "the generic character of this species 

 has not been fully ascertained, but the material from the Yellowstone National Park and 

 specimens from the typical locality at Red Wing, Minnesota, lead me to think that this can not 

 be referred to the genus Billingsella. It appears to be an Orihis of the Plectorthis group of 

 Hall and Clarke." A closer study of this species and the forms referred to Billingsella led me 

 [1905a, p. 246] to refer it to Otusia on account of its surface characters, the character of the del- 

 thyrium in the two valves, and the strong cardinal process and median ridge in the dorsal valve. 



A comparison of the specimens of this species from the type locality at Red Wing, Min- 

 nesota, with those from the Yellowstone National Park shows the two shells to be specifically 

 identical as far as the comparison of casts in sandstone can be made with well-preserved shells 

 on the surface of limestone. 



The specific name was given in honor of Dr. J. H. Sandberg, of Red Wing, Minnesota, who 

 first called attention to the type locality of this species. 



FoEMATiON AND LOCALITY. — Upper Cambrian: (86a) "(St. Croix sandstone^' near Red Wing, Goodhue County, Min- 

 nesota. 



(302f) Upper part of the Gallatin formation, north, side of Elk Pass, between Buffalo and Slough creeks, Yellowstone 

 National Park, Livingston quadrangle (U. S. Geol. Survey), Montana. 



Otusia utahensis n. sp. 

 u 



Plate LXXXIX, figures 3, 3a-c. 



This species is represented by several fragments of the two valves. One of the specimens, 

 represented by figure 3, indicates the general outline of the ventral valve, and figure 3b that of 

 the dorsal valve. The surface is marked by concentric lines and small ridges of growth and 

 numerous fine, rounded, radiating ribs that increase by the division of the ribs as they are 

 lengthened by the growth of the shell. A shallow median sinus occurs on the dorsal valve, 

 and a rounded median ridge on the ventral valve. 



The largest dorsal valve has a width of 9 mm. at the hinge line, with a length of about 6 mm. 



^he generic reference is made on account of the general resemblance of this form to Otusia 

 sandbergi (N. H. Winchell). It differs from the latter in outline and in the rounded character 

 of the ribs. 



Formation and localitt. — Middle Cambrian : (31c) About 900 feet (274.3 m.) above the Brigham quartzite and 

 3,300 feet (1,005.8 m.) below the Upper Cambrian in the limestone forming lb of the Ute limestone [Walcott, 1908f, 

 p. 196], in Blacksmith Fork Canyon, about 10 miles (16.1 km.) east of Hyrum, Cache Comity; (32e) limestone at the 



