°266 PALEONTOLOGY OF NEW JERSEY. 
being fully embraced up to the small umbilicus. Horizontal portion com- 
paratively short and the ventral margin slightly protruding as in S. hippo- 
crepis. Aperture unknown, but from the appearance of the tube near the 
outer geniculation it was apparently contracted both laterally and vertically 
as compared with the size of the tube on the straightened portion. Surface 
marked on the inner coils by comparatively fine and closely arranged 
transverse ridges which become coarser at the inner geniculation, and on 
the straight part and beyond are obsolete; also by two lines of pointed 
nodes on the dorsum, which are prominent, giving a sunken area or appar- 
ent groove on the dorsum between them. Outside of these lines another 
line of nodes occurs at the angle of the back, and two others, less distinct, 
on each side of the horizontal part of the outer chamber. Substance of the 
shell somewhat strong and on the specimens highly iridescent, whence the 
specific name. | 
Septa not very complicated, but rather closely arranged, consisting of 
a moderately large dorsal lobe and three lateral lobes on each side, which 
rapidly decrease in size toward the umbilicus,.on the very margin of which 
the third one is situated. The details of the lobes and sinuses can not be 
traced on any of the specimens in hand sufficiently well to construct a dia- 
gram thereof. The first sinus is much larger than the first lateral lobe, and 
all the divisions of both lobes and sinuses have rounded extremities, and are 
altogether more simple in their structure than those on a specimen of S. 
Conradi of the same size, which is the species most nearly related to it in 
general form and appearance among the American Scaphites. It also differs 
from it in the form of the outer chamber along the ventral edge and in the 
inflation of the middle portion of this part. It resembles that species 
greatly in being circularly discoid, or in the very short horizontal portion. 
Formation and locality: The specimens which I have examined, and 
which are probably all that have been obtained, undoubtedly came from 
Tippah County, Mississippi, from whence Mr. Conrad cites them. The 
specimen originally figured by Mr. Conrad: comes to me in a tray marked 
“S. reniformis Cret. N. J.,” undoubtedly an accidental displacement; while 
the specimens originally belonging in the tray are lost. I have seen no 
example from New Jersey myself that could be referred to this species, 
