144 PALEOZOIC PALEONTOLOGY. 
agree more closely with R. trentonensis (Ulr.) than with any other 
described species, but the specific identification cannot be made with 
any certainty. In such specimens as exhibit the branching of the 
zoarium, the divisions are dichotomous and rather widely spreading. 
About eight rows of zocecia are present on each side of the zoarium, 
the specimens showing but little variation from this number. In 
most cases the external surface of the specimens adheres closely to 
the matrix, and the bifoliate zoarium divides along the mesotheca. 
The material may represent one or more undescribed species. 
BRACHIOPODA. 
LINGULA RICINIFORMIS Hall. 
Plate IX., Fig. 8. 
1847. Lingula riciniformis Hall, Pal. N. Y., vol. L., p. 95, pl. 30, 
figs. 2 a-c. 
1893. Lingula riciniformis Winchell and Schuchert, Pal. Minn., pt. 
I., p. 343, pl. 29, fig. 9. 
Description.—Shell subelliptical in outline, the anterior margin 
regularly rounded, the lateral margins slightly convex, subparallel, 
the postero-lateral margins rounded, the apex rather blunt. The two 
valves equally convex. Surface marked by concentric lines of growth. 
The dimensions of a rather small specimen are: length, 6 mm., and 
breadth, 3.5 mm. 
Remarks.—The little shell identified as this species is not uncom- 
mon in the Trenton limestone of New Jersey. but its condition of 
preservation is such that its distinctive characters cannot be deter- 
mined. In general size and form it resembles L..riciniformis far 
more closely than any other species, so that the identification is made 
with but little hesitation. The individuals studied vary somewhat in 
size, but 10 mm. is about the maximum length which has been ob- 
served. Upon many specimens, in their exfoliated condition, a slight, 
median furrow can be seen, extending backward from the beak to 
beyond the middle of the shell. In a few cases faint, radiating striz 
have been detected in the median portion of the shell near the front. 
