write. ] CARBONIFEROUS FOSSILS. Pet 
The only discovered specimens of this species being crushed or other- 
wise imperfect, it has not been practicable to illustrate it by any other 
figures than the transverse section given on plate 42, although the char- 
acters above’ given have been well ascertained. The exact form of the 
aperture, however, is not accurately known, but the lines of growth show 
the lateral margins to have been sigmoid or sinuous, and the peripheral 
margin concave. These lines also indicate that the aperture was oblique 
to the diameter of the plane of the shell, the peripheral portion retreat- 
ing and the inner projecting. 
Transverse diameter of a volution of less than full adult size from edge 
to edge of the umbilicus, 40 millimeters; width of its sides, 50 millime- 
ters; breadth of peripheral side, 16 millimeters; the full diameter of 
the plane of the largest example discovered, about 130 millimeters. 
The narrow coneave periphery, with its two marginal rows of compressed 
nodes, and the plain, flattened sides of the volutions, which expand 
towards the umbilicus, are characters which distinguish this species from 
all others known to me. / 
Position and locality.—Coal Measure strata, Danville, Il., where it was 
obtained by Mr. William Gurley. 
ARTICULATA. 
VERMES. 
Genus SERPULA Linnezeus. 
SERPULA INSITA White. 
Plate 42, fig. 8 a. 
Serpula insita White, 1878, Proc. Acad. Nat. Sci. Philad., p. 37. 
Scattered through an earthy, Carbonaceous layer of Coal Measure 
strata at Newport, Vermillion County, Ind., are abundant examples and 
fragments of a very small Serpula, which evidently burrowed in the mass 
when it was in the condition of mud. Also sessile upon some imbedded 
molluscan shells are found occasional nearly perfect examples of the same 
species. The species of the genus Serpula are so devoid of distinguishing 
characteristics that a specific diagnosis is often difficult or impossible. 
This species, however, is not likely to be mistaken for any other, because 
of its very small size, and because no other form has been recognized in 
the strata of that age in that region. It is here named, mainly, for the 
purpose of aiding in the classification of the rich fauna of the Carbonit- 
eroas rocks. The species may be characterized as minute, sessile or 
free, tortuous, and subcylindrical. 
