BRACHIOPODA. 399 
Strophomena emaoiata.l 
and short septum, which bifurcates anteriorly. Near the anterior margin of the 
posterior pair of scars two other ridges arise, making four in all, probably the main 
trunks of the vascular system. Very small genital spaces indicated outside the 
muscular scars and in front of the crural plates. 
Ventral valve somev/hat deeper than the other, evenly convex, or with a broad, 
shallow sinus near the anterior margin. Hinge teeth prominent and joining the 
outer elevated margin of the short, suboval, muscular area. This is centrally divided 
by a low ridge, separating the two pairs of adductor and diductor scars. 
This species is of the type of S. sinuata (James) Meek.* S. scofieldi can readily be 
distinguished from the latter by its smaller size and greater number of striae, having 
about sixty. The profound fold and sinus, greater size, and less numerous striae of 
8. sulcata de Verneuil,t will distinguish it from 8. scofieldi. Another related species is 
8. cardinalis Whitfield. J The more elevated cardinal area, very convex dorsal valve 
and greater width of the shell, distinguish this form from 8. scofieldi. 
Formation and locality.— Ra.re near the base of the Galena shales at Minneapolis and St. Paul; 
common in association with Clitambonites diversa at several localities south of Cannon Falls, Minnesota. 
A single specimen of it has been collected near the top of the "Lower Blue beds " north of Beloit, Wisconsin. 
Collectors.— W . H. Scofleld and the writers. 
Mus. Reg. Nos. 8193-8195. 
Strophomena emaciata W. and S. 
PLATE XXXI, FIGS. 22—24. 
1892, April 1. Strophomena emaciata W. and S. American Geologist, vol ix, p. 287. 
Shell small, depressed, biconvex, semicircular in outline; hinge-line usually 
somewhat smaller than the greatest width of the valve. Surface marked by 
numerous angulated striae, increasing in number by interpolation, .having from 
sixty to seventy-five of the large and small ones along the anterior margin. 
Ventral valve depressed-convex, subangulated medially, greatest point of eleva- 
tion about mid-length. Cardinal area narrow, less than 1 mm. in width, strongly 
elevated, with a very convex, apically-perf orated deltidium, which is somewhat 
wider than long and excavated for the reception of the chilidium. 
Dorsal valve slightly convex, with or without a shallow sinus, having its origin 
near the beak and rapidly widening to the anterior margin, which is more or less 
sinuous, according to the depth of the medial depression. Cardinal area linear, with 
a short, broad chilidium partially covering the cardinal process. Interior unknown. 
This little species was at first regarded as the young of some form of 8tropho- 
mena. There are two species] associated with it — 8. scofieldi and 8. trentonensis. If 
*Pal. Ohio, vol. 1, p. 87, pi. v, figs. 5a— 5f. 
tibldem, p. 85, pi. v, tigs. 4a-4e. 
.t*Geol. of Wise, vol. Iv, p. 261, pl.:xii, figs. 9, 10. 
