BILLINGSELLIDiE. 769 



Oeusia lenticularis atetpoides (Matthew). 

 Plate XCVIII, figure 5. 



Orthis lenticularis atrypoides Matthew, 1892, Trans. Roy. Soc. Canada for 1891, vol. 9, sec. 4, No. 5, p. 48, PI. XII, 

 figs, lla-b. (Characterized as a new variety; see below for copy. The specimen represented by fig. 11a is 

 redrawn in this monograph, PL XCVIII, fig. 5.) 



Orthis lenticularis atrypoides Matthew, 1903, Geol. Survey Canada, Kept. Cambrian Rocks Cape Breton, p. 217, PI. 

 XVII, figs. 3a-b. (Characterized. Figs. 3a-b are copied from Matthew, 1892, PI. XII, figs, lla-b, respec- 

 tively.) 



Orthis (Oricsia) lenticularis atrypoides (Matthew), Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28, p. 276. (Original 

 characterization copied as below.) 



The original description by Matthew follows : 



This form is comparatively smooth, though the ventral valve is sometimes concentrically wrinkled. This valve 

 is distinguished by a medlar -idge and somewhat flattened sides, and the dorsal valve has an unusually deep sinus. 

 Size of the known examples, 6 by 6 mm., and 5 by 6 mm. for the two valves. 



Formation and locality.— Upper Cambrian: (308b [Matthew, 1892, p. 48]) Limestone lentils in black shales 

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



Orusia lenticularis lyncioides (Matthew). 

 Plate XCVIII, figure 4. 



Orthis lenticularis lyncioides Matthew, 1892, Trans. Roy. Soc. Canada for 1891, vol. 9, sec. 4, No. 5, p. 49, PI. XII, 

 figs. lOa-c. (Characterized as a new variety; see below for copy. The specimen represented by fig. 10a is 

 redrawn in this monograph, PI. XCVIII, fig. 4.) 



Orthis lenticularis lyncioides Matthew, 1903, Geol. Survey Canada, Rept. Cambrian Rocks Cape Breton, p. 216, PI. 

 XVII, figs. 2a-c. (Characterized. Figs. 2a-c are copied from Matthew, 1892, PL XII, figs. lOa-c, respec- 

 tively.) 



OrfMs {Orusia) lenticularis lyncioides (Matthew), Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28, p. 277. (Original 

 characterization copied as below.) 



^he original description by Matthew follows: 



Distinguished by its sharp, strong, radiating ribs, large umbo, and high cardinal area. In some of the larger 

 examples the radiating ribs become subordinate to and are replaced on the newer part of the shell by concentric strije 

 reversing the usual position of the ribbed and the smooth parts of the shells of this species. Size of the valves about 

 6 by 8 mm. 



I have illustrated a ventral valve from Matthew's material that is the most strongly marked. 

 The ventral valves are similar to those from Newfoundland represented by Plate XCVIII, 

 figures 2h and 2i. 



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

 of Division C3a of Matthew's sect^'on, Germaine Street, St. John, St. John County, New Brunswick, Canada. 



Genus OTXJSIA Walcott.a 



Billingsella (Otusia) Walcott. 1905, Proc. U. S. Nat. Mus., vol. 28, p. 246. (Mentioned as a new subgenus.) 



Otusia Walcott, 1908, Smithsonian Misc. Coll., vol. 53, No. 4, PI. XI, and pp. 142 and 148. (Classification of genus.) 



This name was proposed [1905a, p. 246] to include " Orthis sandbergi" of N. H. Winchell, 

 which was the only species known at the time the genus was named. One new species, Otusia 

 utahensis, has been added since. The generic and specific characters are included in the descrip- 

 tion of the sf)ecies. 



Otusia sandbergi (N. H. Winchell). 



i-^ Plate XCIII, figures 4, 4a-d. 



Orthis sandbergi N. H. Winchell, 1886, Fourteenth Ann. Rept. Geol. and Nat. Hist. Survey Minnesota, p. 318, PI. II, 



figs. 8 and 9. (Described as a new species.) 

 Orthis {">) sandbergi Winchell, Walcott, 1899, Mon. U. S. Geol". Survey, vol. 32, pt. 2, pp. 452-453, PL LXI, figs, 2, 2&-d. 



(Described and discussed as on p. 770. Figs. 2, 2a-d are copied in this monograph, PL XCIII, figs. 4, 4a-d, 



respectively.) 



a Prior to the definition of tlie genus Otusia the type species was described under the genera Orthis N. H. Winchell [1886, p. 31SJ and OrtMs ? 

 Walcott [1890, p. 452]. 



62667°— VOL 51, ft 1—12 49 



