MIOCENE MOLLUSCA AND CRUSTACEA. ilsi7/ 
occupied by six radii on one, there are ten in the other; one of these has 
the strix strongest on the narrow end and the other on the broad end. 
There are equal variations in the arcuation of the back of the shell, and in 
the size and the form of the fissure. The general outline of the base in its 
elongate-ovate form is perhaps the most constant feature of the species. 
Considering the degree of variation it is not surprising that there should be 
some discrepancy between the two descriptions quoted from Mr. Conrad, 
written at different times and probably from different individuals. 
Formation and localities: The species has been recognized from the gray 
marls at both Shiloh and Jericho; and in the stony layers near Bridgeton 
and in the brown clay near Shiloh, N. J. In collections from Rutgers Col- 
lege, the National Museum, and the Academy of Natural Sciences at Phila- 
delphia. 
- Order TECTIBRANCHIATA. 
Family TORNATELLID4#=ACTAZAONID2. 
Genus ACTAON Montfort. 
ACTON SHILOHENSIS, n. sp. 
Plate xxIv, figs. 15-17. 
Shell of about medium size, subglobular or broadly ovate, the trans- 
verse diameter being to the height about as three to five; spire short, the 
apical angle about 70 degrees. Volutions six, short in the spire, abruptly 
rounded on the top, giving an almost impressed suture line, and _pre- 
senting a step-like appearance to the spire, rounded and full below; 
aperture moderately large, somewhat effuse below, the outer lip sharp; 
columella short and the fold very distinct and defined. Surface polished, 
with nearly equidistant impressed lines; except on the upper third of the 
height or on the exposed portion in the spire, where they are obsolete; 
lines generally clean, or free from puncte or dots. Some of the interspaces 
on the lower part of the volution marked by an intermediate finer-line. 
This species differs from several forms known in the Eocene formation 
in being more globular, and in having a shorter spire. 
Formation and locality: In the gray marls of the Miocene at Shiloh, 
N. J. From the collection of the National Museum. 
