NERIN AA. 195 
Where the ornaments have been preserved we find very fine spiral lines, whose 
granulations can only be seen under a lens of some power; these lines have a 
tendency to die out in the more mature whorls. Rich tubercular ornamentation 
is rare, and would seem mainly confined to species from the highest beds of the 
Lincolnshire Limestone, which appear to have Bathonian affinities. 'The mature 
whorls sometimes show the curving lines of growth and the slight raised line on 
the posterior margins, but too often almost every surface feature is obscured. 
Although there is considerable uniformity in the section of an individual 
Nerineza, that is to say, that the folds vary but little in the several whorls, yet there 
does seem a tendency in many cases for the mature whorls to be less restricted as 
to internal space. It may be that the folds of the body-whorl were more or less 
absorbed, so as to give the animal additional space. I have noticed, especially in 
Ptygmatis, this tendency of the folds to diminish, and indeed to become almost 
effete in the body-whorl. Mr. Witchell also noticed this feature, and attributed it 
to wear. It is not a little singular that when we obtain an unbroken shell, as is 
frequently the case in the Oolite Marl horizon, there is no trace of folds to be 
found, either on the lip or columella. 
Definition and Range of Species —When Lycett wrote ‘ The Cotteswold Hills,’ 
in 1857, he enumerated no more than six species of Nerinxain the Inferior Oolite 
of the Cotteswolds. In 1887 Witchell had brought up the number to twenty. In 
the present Monograph certain forms have been named provisionally, but not 
described as distinct species. Some of the forms described as species to a certain 
extent run into each other, and it may be predicted that future collectors are sure 
to find an increased number of intermediate forms. Moreover, many of the 
species appear to be local, and often limited in range. A few are useful as indi- 
cating horizon, but it would seem as though still fewer could be relied upon for 
any great distance. The most marked Nerinwan horizon known to me is that of 
N. Guisei in the Clypeus-grit. The varieties of N. Cotteswoldixz also help to 
connect both the Pea-grit and Oolite Mar! with certain horizons in the Lincolnshire 
Limestone. 
Nerinzas of the Lincolnshire Limestone.—To a certain extent these require 
separate treatment, especially as regards specimens from Weldon and Great 
Ponton. The species at Weldon are extremely numerous, including examples of 
Nerinella, Nerinxa, and Ptygmatis, though Nerinza greatly preponderates. Many 
are very small, and nearly all have suffered either before or since mineralization. 
There seems to be a great admixture, suggesting the possibility of some of the 
1 As regards ornamentation it is curious to note what different artistic treatment has been 
accorded to the same species. Thus, WV. funiculus, Desl., NV. clavus, Desl., WV. pseudocylindrica, D’Orb., 
are represented in Deslongchamps’ work as having fine spiral ornamentation, whilst in D’Orbigny’s 
figures of the same species the spiral ornamentation is entirely ignored, and a very elaborate system of 
growth-lines is substituted. 
