PURPURA. 281 



According to him it deposits its spawn all tlie year 

 rounds but more actively from January to April. Spawn 

 which he collected in January 184^3 was hatched four 

 months afterwards ; he took 47 fry from a single cap- 

 sule. They soon began to assume the peculiar habit of 

 their parents, " by getting out of the water, where they 

 would remain for hours, answering to the period of the 

 ebb and flow of the tide.''^ Cailliaud counted 245 cap- 

 sules which had been produced by a single Purpura 

 about the same time ; each capsule contained from 16 

 to 28 perfect embryos [making therefore an average 

 total of 5390] : they were hatched in turn by the parent, 

 which (as he supposes) thus not only supports them by 

 her nutritious moisture, but protects them against 

 accidents. I have only seen the Purpura covering with 

 her shell the egg-cases while they were being laid. M. 

 Cailliaud adds that some of the inhabitants of St. Michel- 

 Chef-Chef eat this shell-fish after the spawning-season. 

 It does not seem to be anywhere else an article of food — 

 although our remote ancestors were probably less fasti- 

 dious in their tastes; for the shells are found in the 

 refuse-heaps or kitchenmiddens of ' Picts ' houses^ near 

 Wick, mixed with shells of the common periwinkle, and 

 occasionally of the limpet and mussel. Within the period 

 of civilization this mollusk has been made useful in 

 another way ; and a great deal has been published con- 

 cerning the purple dye which is yielded by our Purpui^a, 

 as well as by that of the Greeks and Romans. The Vene- 

 rable Bede mentions it, in terms of admiration, in his 

 Ecclesiastical History of England : as to its permanency, 

 he says, '' quo vetustior, eo solet esse venustior."^ The 

 subject has been since discussed, in both an economical 

 and philosophical point of vicAv, by a crowd of writers, 

 English, French, Norwegian, Spanish, Italian, German, 



