MURICID^. 109 



Distr. — 51 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 in a ver^^ 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 

 usuall}^ 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 revei'sed, as well as a 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 digesting its 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 Linne to eat the dead fish left in fishermen's nets. I 

 have seen it busily feeding on Balanus balano'ides, its strong- 

 proboscis being inserted between the opercular walls of the bar- 

 nacle. According to Mr. Osier, it also devours Littorinse, Trochi, 

 Naticse, 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 

 extremel}^ fine scratch-like striae, 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. Osier 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 



