ti-- I'he AnierifdJI (rCohxjisf. October, 1«95 
sal saddle hardly as lon^ as the dorsal lobe, but wider, and 
rounded at the extremitv. Upper lateral lobe shallow and 
rounded at the end. Lateral saddle shallow, broad and 
rounded. Lower lateral lobe broad, obtuse. From the um- 
bilieus to the dorsal side of a volution, three well defined, 
equi-distant furrows extend. Bod}^ chamber not present in 
the specimen figured.. The average size of the twelve or more 
specimens in the collection is little more than half that of the 
example figured. 
Obtained from the clay partings between the lower two 
layers of the Lithographic or Louisiana limestone at Louisi- 
ana, Mo. Com])are with Dr. A. WinchelTs (t. ini(iiii(i-ii.s from the 
Marshall grouj). 
PLEUROTOMARIA MINIMA, sp. nov. 
Fig. 19. Lateral view of a large specimen of the species, greatly mag- 
nified. 
Outline of shell, low trochiform, minute. Volutions pre- 
served rarely more than three, increasing rapidly in size. A 
narrow spiral band (luite noticeable around the middle of the 
first volution. Suture well defined. Umbilicus small. Surface 
apparently ornamented by transverse lines, visible only on a 
single specimen. Aperture subcircular. Length and breadth 
of specimens about equal. One-seventeenth of an inch in di- 
ameter. 
Collected from the clay parting between the lower two lay- 
ers of the Lithographic or Louisiana limestone at Louisiana, 
Mo. 
MURCHISONIA (7) PYGM/EA. sp. nov. 
Fig. 20. Lateral view of a specimen greatly magnified. Tlie figured 
specimen preserves six rounded volutions. 
Shell minute, elongate, slender, tapering very gradually. 
Volutions roundeil, the lowest being quite as long as the two 
whorls above. Suture well defined. No surface ornamenta- 
tion visible, probably on account of the pyritized condition 
of the specimens, which after all may be but casts. Natural 
size of the figured specimen one-sixteenth by one-fortieth of 
an incii. A rare species. 
Collected from the clay parting between the lower two lay- 
ers of the Louisiana or Lithographic limestone at Louisiana, 
Mo. These shells were obtained while w^ashing the clay for 
young brachiojiods and were found associated with AlUajecri- 
