KUTORGINID^. 583 



of the intervening ridgelets a beaded appearance; at certain intervals stronger concentric strise of growth show on the 

 surface of the shell; there are about five or six of these on its surface. 



Length, 4 mm.; width, 6 mm.; depth of the ventral valve, 1.5 mm. 



This species is smaller than K. cingulata and differs in its ornamentation. 



Observations. — This little shell occurs in reddish hmestone beneath a shaly band in which 

 I found fragments of Olenellus. Except for size it is much like Kutorgina cingulata (BiUings) 

 in its general aspect. It differs in the details of surface ornamentation and interior radiating 

 lines. 



The form owes its specific name to its granulated surface. 

 Formation and locality. — Lower Cambrian: (314b [Matthew, 1899e, p. 97]) Limestone of the "Etcheminian 

 series," at Smith Sound, Trinity Bay, Newfoundland. 



Kutorgina peculiaeis (Tate). 



V Plate V, figure 2. 



Orthis {?) peculiaris Tate, 1892, Trans. Roy. Soc. South Australia for 1892, vol. 15, pt. 2, pp. 185-186, PI. II, fig. 5. 

 (Described as a new species; see below for copy. The specimen represented by fig. 5 is redrawn in this mono- 

 graph, PL V, fig. 2.) 



The original description by Tate follows : 



Transversely subquadrilateral, equilateral; hinge-line in the longest anteroposterior [transverse] diameter, 

 straight. 



Ventral (?) valve flatly convex, with an abruptly depressed and deeply bUobed ventral margin; the mesial 

 furrow decreases in depth as it ascends to near the umbo; the lateral margins are obliquely arched, nearly straight, 

 forming an angle of about 70° with the hinge-line. 



Surface marked by depressed unequal folds of growth. 



The author [1892, p. 185] referred to the valve as ventral (?). Its reference to Kutorgina 

 identifies the valve as the dorsal. I do not know of a closely related form. 



The form owes its specific name to the fact that it seemed to be an unusual representative 

 of the genus to which it was first assigned. 



Formation and locality. — Middle? Cambrian: (318a) Limestone at Parara, near Ardrossan; and (315) lime- 

 stone at Curramulka; both [Tate, 1892, p. 185] in Yorke Peninsula, South Australia. 



Kutorgina perugata Walcott. 



Plate V, figures 3, 3a-e. 



Kutorgina perugata Walcott, 1905, Proc. U. S. Nat. Mus., vol. 28, p. 310. (Described and discussed essentially as 

 below as a new species.) 



General form ovate, biconvex. Surface marked by concentric lines of growth and more 

 or less strong concentric corrugations. The outer surface is ornamented by a fine network 

 of oblique depressed lines that leave minute rhomboidal elevations between them that look 

 like fine papillse under a moderately strong magnifier, and the cast of the surface has much 

 the same appearance in a transverse light. Shell substance calcareous. 



A large ventral valve has a length of 14 mm., width 16 mm. A dorsal valve 11 mm. 

 in length has a width of 14 mm. 



The ventral valve is strongly convex in adult shells, with the liighest point near the umbo 

 or at the apex; the apex terminates at or overhangs a rudimentary pseudo-area that slopes 

 beneath the shell at an angle of 45° to 60° to the plane of the margins of the valve; the pseudo- 

 area is concave and about half the length of the space between the apex and the plane of the 

 valve. Casts of the interior show well defined main vascular sinuses, with the outline of the 

 visceral area between them. 



The dorsal valve is transverse, nearly flat in some examples and slightly convex in others. 

 The surface slopes gradually from the margins to near the umbo, where the slope increases 

 and extends to the upward-pointing apex; a rudimentary pseudo-area slopes backward from 

 the apex. In some examples the pseudo-area appears to be little more than a bending over 



