cragin.] DESCRIPTIONS OF SPECIES. 107 
breadth about equal (25 mm.), yet having their greatest breadth in 
the lower part. The involution is between J an d h The ribs are 
heavy and inclined forward; mostly bifurcate at about the middle 
of the flank, but in one instance a rib is seemingly bidichotomous, 
the first bifurcation taking place on the umbilical border. The ven- 
tral ribs pass over the periphery without interruption, but are curved 
forward as they approach the median line so as to make a very obtuse 
angle, at which many of them suffer a very slight weakening. The 
specimen does not show the largest part of the last whorl, a fact 
to which the almost uniformly bifurcate character of the ribbing i< 
probably due. 
Doctor Stanton also has collected at this locality a small specimen 
that apparently represents the inner whorls of the same species. 
This has many of the ribs once bifurcate, the others simple. 
The following is a translation of the original description of the 
species : 
Shell discoidal, spire composed of embracing whorls of nearly round cross 
section, visible in the umbilicus in a third of its width, having its major thick- 
ness near the umbilical border; flanks convex, descending gradually toward the 
umbilicus; siphonal region perfectly rounded. Umbilicus small, rather deep, its 
border not angulated. Surface covered with 4G to 48 strong, equal costelhe 
which bifurcate, some at the middle of the flanks and others a little earlier; 
of the former some trifurcate and the latter undergo a second bifurcation, 
which takes place at the same distance from the umbilicus as that of the other 
costella\; three or four ribs remain simple; all cross the siphonal region form- 
ing a slight forward inflection. Aperture a little higher than wide, a little 
invaded by the whorl of the spire and rounded above. Three narrow constric- 
tions [sitrcos] are seen, shallow and parallel to the costelhe. Diameter 60 mm.. 
75 mm.; breadth [height] of the last whorl with relation to the diameter 0.38, 
0.38; thickness of the last whorl with relation to the diameter 0.38, 0.38; diame- 
ter of the umbilicus with relation to the diameter 0.35, 0.33. 
Perisphinctes schucherti sp. n. 
PI. XXV, fig. 1; PL XXVI, tigs. 1-3; PI. XXVII, fig. 1. 
Shell discoidal, moderately involute, each whorl embracing about 
a third of its predecessor: the umbilicus strongly excavated, its span 
equaling about a third of the corresponding diameter of the shell : 
whorls laterally compressed, even the earlier ones being much higher 
than wide, the flanks flattened-convex, narrowed toward the siphonal 
side, which is rounded, umbilical border rounded above, descending 
almost sheerl} r below to the surface of the inner whorls: septal line 
with two lateral lobes, of which the first is large, ample-trunked and 
longer than the siphonal lobe, and ends in three branches, the second 
lateral lobe being well developed and considerably more than half as 
long as the first, suspensive lobe (nahtlobus) of intermediate steep- 
ness, presenting one conspicuously large auxiliary lobe; ribs gently 
