298 
DEVONIAN FAUNA. 
tinct median line. Snrface nearly smooth, ornamented by fine irregularly grouped 
growth-lines, that start perpendicularly from the suture, arch back to the sinus- 
band, which they cross in a shallow concave arc or curve, and then seem to 
become rather stronger on the base of the shell. Surface below the suture some- 
times covered by multitudinous, very fine, low, close, rounded threads. Umbilicus 
large and deep. Mouth emarginate, sub-circular or sub-elliptic. Lips sharp, 
continuous. Shell-structure rather thin. 
Size. — Height 42 mm., width 42 mm. A small flat specimen measures 9 mm. 
high, 14 mm. wide. 
Localities. — In Mr. Vicary's Collection are three specimens from Ohudleigh 
and thirteen from Wolborough ; in my Collection two from Chudleigh and one 
from Wolborough ; in the Torquay Museum six, some probably from Lummaton 
and some from Wolborough ; in the Museum of Practical G-eology three from 
Wolborough ; and in the British Museum one from Lummaton and one from 
Wolborough. 
Remarhs. — Helicites delpJiinuloides, Schlotheim, is a very common and well- 
known shell, which has been frequently figured and described under various 
names by foreign authors. These figures show the great variability of the species, 
and the same fact is borne out by an examination of our English examples. 
They vary greatly in the height of the spire, the rate of increase and number of 
the whorls, and the shape of their section. Unfortunately these specimens are 
for the most part defective or decayed and cannot therefore be compared as com- 
pletely as could be wished. In spite of their variability, however, they all appear 
to have the same general character, and there is little doubt that they all belong 
to Schlotheim's species. His figure represents a specimen of medium height, and 
shows the broad sinus-band bounded by a raised thread, and the obliquely longi- 
tudinal striae above and below it. 
D'Archiac and de Verneuil and also Sandberger figure two extreme varieties, 
and the former authors suggest that one of theirs, which is exactly like the most 
elevated of our shells, may possibly prove to be a distinct species. The specimens 
now before us from their constant variability do not point to this, and probably 
the possession of a few more good examples would fill up the gaps which still exist. 
Sandberger gives no reason for changing the name of his shell. 
Eu. delpliimdiforinis as given by Eichwald is much more elevated, and perhaps 
increases less rapidly ; but in view of the variability of the species it may probably 
be regarded as simply a variety. It is longer than wide, and smooth except for 
the sinus-band. 
Euomphalus Dionysii ? F. A. Romer looks just like the cast of a rather elevated 
form of this shell. Some of Mr. Vicary's specimens almost exactly agree with 
Romer's figure. In his later work, however, Romer refigures his species mider the 
