NERIN AVA. 193 
“ How and whence did they come, these curious cylindrical shells with their 
internal folds? Such a question must occur as a matter of course to everyone 
interested in Jurassic paleontology. . . . . Does the evidence at present in 
our possession lead us to suppose that they appeared almost simultaneously along 
the whole line, or earlier in one place than another? We may fairly believe that 
these shells originated in the calcareous shallows which succeeded the more sandy 
deposits of the Oynocephala-stage towards the base of the Inferior Oolite.” 
Since the above was written the attention of Mr. Witchell and others has 
been drawn to this very question, and I myself have had many opportunities for 
extending the investigations, which originally commenced in Yorkshire, into the 
Midland and South-western Counties. The following is a partial summary of the 
results. 
There is no authentic evidence of the existence of Nerinza in the British Lias, 
although the late Charles Moore enumerates four species.'. In Yorkshire Nerinza 
has not yet been detected below the Nerinza-bed which occurs in the upper part 
of the Dogger at Blue Dyke. Here a well-known and well-developed form 
(N. cingenda, Phil.) suddenly appears in abundance, and a large variety of the 
same species appears with equal suddenness in the Northampton Sand. In the 
Cotteswolds several species of Nevrinzxa appear in the Pea-grit, mostly cylindrical 
forms belonging to the sub-genus Ptygmatis. These are undoubtedly in the 
Murchisonx-zone. But in the shell-bed below the Lower Limestone at Crickley 
Hill, in what is perhaps the top of the Opalinus-zone, occurs a Nerinea (Ptygmatis) 
to which I have given the specific name of xenos, possessing an internal structure 
considerably different from that of NV. cingenda. This appears to be the oldest form 
of Nerinea hitherto discovered in the Cotteswolds, and it serves to bear out the 
general conclusion that the genus, as far as this country is concerned, makes its 
first appearance on the confines of the zones of Am. Murchisone and Am. opalinus. 
In Dorsetshire, on the other hand, where a strong cephalopod facies characterizes 
all the zones, Nerinxa is as unknown in the Inferior Oolite as in the Lias.’ 
We owe much of our knowledge of the Nerinzeas of the Cotteswolds to the 
ability and enthusiasm of the late Mr. Witchell, of Stroud, who literally died at 
the edge of his favourite quarry on Swift’s Hill, whither he was in the habit of 
repairing for the purpose of extracting fossils. In his admirable paper “ on the 
genus Werineza and its stratigraphical distribution in the Cotteswolds” Mr. 
Witchell enumerates twenty species from the Inferior Oolite of that region, these 
being classified under five groups according to their internal structure. 
It is well known that many attempts have been made to subdivide this 
1 Some of these are founded on very imperfect fragments. ‘‘ Nerinwa” liassica is stated by 
Mr. Walford to be a Cerithiwm, as proved by the section. 
2 For further information relative to the distribution of Merinwa see Introduction, especially 
p- 61. ne 
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