304 Unwersity Geological Survey of Kansas. 
lecta (Gein.) and Schizodus wheelert Swall. occur occasionally, 
at least, except in the Cherokee shales. 
EKuphemus carbonarius (Cox) is found fairly continuously, 
for a gastropod, throughout the series, while Bellerophon cras- 
sus M. and W., Euomphalus catilloides (Conr.) and Patellos- 
tium montfortianum (N. and P.) occur occasionally through- 
out the section above the basal member, Huomphalus catilloides 
(Conr.) being the most prominent and the most continuous in 
its occurrence. 
None of the cephalopods are found both in the uppermost 
and lowermost horizons. Those approximating it most closely 
are “Orthoceras” rushense McChes. and Tainoceras occidentale 
(Swall.), occurring at intervals above Stage A. 
Griffithides scitula M. and W. is the only trilobite that ranges 
nearly through the whole section. It has not yet been found in 
the Cherokee shales nor in Stage H. 
We cannot drop this discussion without recalling an idea 
differently stated in another chapter. If the species given in 
these lists were divided as they are by some paleontologists, 
the range of several of them would be considerably restricted 
and the number of species considerably increased. In these 
lists the specific lines are rather loosely drawn in some in- 
stances. This is particularly true of some of the species 
of Productus. But there are other species which hardly 
fall in this class. Some paleontologists describe species 
closely and without any reference to the life-history of the 
species, giving each stage a separate specific name. On the 
other hand, there are those who include in a species all the 
forms found throughout a series of sediments, with all the 
variations due to the life-cycle. Then there is a third class, 
who describe these different stages as varieties, in which case 
they are indistinguishable from local variations, so far as the 
nomenclature goes. However, they may be distinguished by 
varieties if certain adjectives are used, such as “geronticus,” 
“senelis,” “moritura,” etc., which would designate the rela- 
tionships of the varieties. 
Thus Seminula argentia (Shep.) might be described under 
two, and, more probably, three species, with definite limited 
range, or as a single species with a very great range, or as a 
species and two varieties, the latter with limited vertical dis- 
tribution. In the same way Chonetes granulifer Owen could 
