MURICID. 109 
Distr.—5i sp. All parts of the world, low water to 25 fathoms. 
P. Persica, Linn. (xliv, 16). Fossil, 40 sp. Tertiary—. 
Shell oblong-oval, last whorl large; spire generally short; 
aperture ovate, large, terminating ina very short, oblique channel, 
or notched ; columella flattened ; outer lip simple. 
The animal does not differ essentially from that of Murex in 
its general external and anatomical characters. The eyes are 
usually placed near the tips of the tentacles, the siphon is short, 
and the foot not large. 
This is one of the genera from which the ancients obtained 
dyes; by pressing on the operculum of P. lapillus (xliv, 22), a 
fluid will be obtained which colors a dull crimson. The metrop- 
olis of this form is Northern Europe; the North American speci- 
mens, as well as those from Southern Europe and North Africa, 
being stunted in comparison of size and ornamentation. Its fossil 
distribution ascends as far back as the Red Crag of England. 
It lives gregarious on rocks and stones within the tides, where it 
preys on mussels, limpets, and barnacles. It is especially fond 
of oysters, and is considered a destructive enemy by the culti- 
vators of the bivalve. A single reversed, as well asa scalaroid 
Specimen are recorded by Mr. Gwyn Jeffreys. He says that ‘this 
mollusk has a shambling gait and sedentary habits, and seems to 
be always eating or digestingits food. Lister, however, observed 
it early in the morning, at the commencement of June, otherwise 
engaged, viz., in perpetuating its species on a dry rock after the 
tide had receded. It is very destructive to mussel-beds, and is 
said by Linné to eat the dead fish left in fishermen’s nets. I 
have seen it busily feeding on Balanus balanoides, its strong 
proboscis being inserted between the opercular walls of the bar- 
nacle. According to Mr. Osler, it also devours Littorine, Trochi, 
Natice, and even its own kind. From what I have observed of 
the mode by which it perforates the shell of a mussel, I am 
inclined to agree with Mr. A. Hancock, that it uses its tongue. 
I cut off the end of the proboscis of a Purpura while it was 
attacking a mussel; the part thus lopped still remains in the 
hole, with the front of the tongue exposed. The hole is shaped 
like an inverted cone, and exhibits under the microscope 
extremely fine scratch-like strive, as if caused by the rasping 
action of the lingual apparatus. I believe the movement to be 
rotatory, because the sides of the hole are quite even. The 
process is an extremely slow one. Mr. Osler states that, after 
watching for some hours a Purpura attached to a Limpet, he 
found the perforation incomplete; and Mr. Spence Bate and 
Mr. Bretherton noticed that it took two days to get through 
the shell of a moderate-sized mussel. It does not appear that 
the prey is destroyed by any poisonous secretion of the whelk, 
after it has gained access to the interior. The proboscis is at 
