PORCELLIA. 
331 
whorl as to be very nearly as deep as the umbilicus. Suture deep, rectangular, 
facing upwards. Whorls rising steeply from the suture with a slight outward 
bend till they reach the highest point of the shoulder, where they curve more or 
less rapidly and then slope out obliquely to the widest point, where they become 
almost horizontal, and then curve back below in a way similar to the upper 
surface ; the greatest width of the shell being marked by a small narrow deep 
channel or groove. Ornament consisting of very fine, sharp, radiating threads, 
separated by their own width, which rise perpendicularly from the suture, and after 
crossing the shouldei', where an intermediary series of similar ribs come in, 
diminish in size and bend gently rearwards as they approach the back. 
8ize. — Height 9 mm., width 28 mm. 
Localities. — From Wolborough there are six fine specimens in Mr. Vicary's 
Collection, one in the British Museum, two in the Museum of Practical Geology, 
and one in my own Collection. There are twelve specimens in the Torquay 
Museum, some of which are from Wolborough, and some from Lummaton or 
Barton. 
Bemarlcs. — This shell was described by Phillips in his ' Palseozoic Fossils ' as 
Bellerophon Woodwarclii, Sowerby, but the identification is certainly erroneous. 
He made it from a single Devonshire specimen in which, as he intimates, the 
ornamentation was obliterated. Hence the spiral striation, which is indicated 
both in his figure and description, was clearly filled in from the Carboniferous 
shell. Though many of the specimens, which I know, are decorticated after the 
manner so frequent in Wolborough fossils, yet in each of the collections mentioned 
above are examples which preserve the sculpture, and they show distinctly that 
it is of a radiating and not of a spiral character. In most of these it is seen that 
these radiating strise become smaller and more numerous on the outer part of 
the shell, though it is not quite clear whether this arises from divarication or 
from the rising of an alternate series of strige. Another distinction between the 
Carboniferous and Devonian species is the much greater angularity of the former, 
so that even if the ornament had remained unknown the distinctness of the 
present shells, which exactly correspond with Phillips' figure, could have been 
easily established. 
The angle at the shoulder seems to be considerably more pronounced in the 
older and larger speeimens, and, as seen in one of the Torquay examples, the 
symmetry is not quite perfect, the umbilical side being slightly steeper than 
the upper. 
It appears to be the same shell as Pleurotomaria bifida, Sandberger. Possibly 
the section of the whorls is a little more angular in the full-grown English shells, 
but the general appearance, the bifurcating ornament, and the variability in the 
coarseness of the strije and in the angularity of the shoulder are the same in both 
43 
