BRACHIOPODA. 389 
Stroph oiijf iia trenf oneiisis. ] 
This variety in general appears to be closely related to Strophomena wisconsinensis 
Whitfield,* but is readily, distinguished in being less convex and in the very distinct 
alternation of the striaj. That species is clearly related to S. rugosa Blainville, while 
S^negleda, var. acuta belongs to the S. incurvata group of strophomenas. Strophomena 
vetusta James** is probably also closely related, but it is more evenly convex, never ^ 
has a flat central disc in the dorsal valve, while the outline is subquadrate. 
Formation and locality.— ^ot rare in the upper portion of the Hudson River group at Spring Valley, 
Minnesota. 
Collectors.— Ei. O. Ulricli, W. H. Scofleld and the writers. 
Mus Reg. No. 5550- 
Strophomena trentonensis, n. sp. 
PLATE XXX, FIG. 41. 
1847. Leptcena subtenta (partim.) Hall. PalaBontology of New York, vol. i, p. 115 
1883. Streptorhynchus subtenta Hall. Second Annual Report, New York State Geologist, pi. xxxix, 
fig, 18. 
1892. St7'ophome7ia subtenta HALL. PaUeontology of New York, vol. viii, pt. i, p. 251, pi. ix, fig. 18. 
This species is closely related to S. rugosa var. subtenta. The valves are, however, 
thinner, the striae more delicate and the oblique wrinkling along the cardinal mar- 
gins a more constant feature than in that species. The interior characters of S. 
trentonensis are also less strongly developed than in 8. rugosa. Whether from New 
York, Minnesota, Kentucky or Tennessee, they exhibit the same undefined internal 
markings when compared with the Hudson River group specimens of the latter 
species. It is deemed also advisable to indicate this line of development towards 
S. rugosa of the Hudson River group by separating the Trenton specimens on the 
above characters with the name S. trentonensis. 
Prof. Hall {op. cit, 1847) found among the drawings of Mr. Conrad the figure of 
a Strophomena with the name S. subtenta attached. The specimen from which this 
drawing was made Prof. Hall says "is from a western locality" of the upper portion 
of the Hudson River group of Ohio or Indiana. This form was again described and 
figured by Meekf as S. plicata. As the essential difference between this form and 
S. rugosa is only in the oblique wrinkling of the shell along the cardinal margins we 
do not consider it of greater importance than varietal. 
Formation and locality. — Not common in the Trenton shales at several localities to the south of 
Cannon Falls, Minneapolis and Fountain, Minnesota. In the "Lower Blue beds'' at Janesville and 
Beloit, Wisconsin. Near the top of the Trenton at Frankfort, Kentucky, and Nashville, Tenne.ssee; 
Trenton Falls, New York. A few examples apparently of this species have also been found in the Galena 
shales in Goodhue county, Minnesota. 
Collectors.— 0. L. Herrick, W. H. Scofleld and the writers. 
Mus. Reg. Nos. 677, 8179, 8182, 8183. 
*Gool. Wis., vol. Iv, p. 2lj:j, pi. xn, figs. U-13; 1881 
**Cinciunatl Quart. Jour. Sci. vol. i, p. 241; 1874. 
tPal. Ohio. vol. i. p. 81, pi. vi. Hijs. 4a-4h. 
