110 MURICID A. 
first thrust into the hole which it had drilled,and the whelk eats 
in that way; but when, from the death of the mussel or limpet, 
the former gapes or the latter separates from the rock, the Pur- 
pura devours the remainder by the natural opening. 
“ According to Mr. Peach, it deposits its spawn all the year 
round, but more actively from January to April. Spawn which 
he collected in January, 1848, was hatched four months after- 
wards; he took forty-seven fry from a single capsule. 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.”—JEr- 
FREYS, Brit. Conch., iv, 279. 
Like all other predacious and voracious beasts, the Purpura 
meets with retribution occasionally ; here is an instance : 
Mr. Henry Crowther, whilst collecting in the shore pools at 
Whitby, England, “noticed a commotion amongst the mollusks 
which was of too brisk a nature for their well-known and char- 
acteristic slowness. When the obscuring sands which they had 
thrown up in the fray had settled, he saw that the shells were 
principally in the possession of hermit crabs, which, under this 
guise, were attacking a Purpura lapillus and dragging it from 
its shell. We caught the whole school at once and transferred 
them to a collecting-bag ; the shells occupied were Nassa pyqmea, 
Trochus cinereus, Littorina littorea, three sizes,and a P. lapillus, 
the sheik of the party, for he was taken red-handed. We pre- 
sume to think that if their object had not been frustrated, 
there would have been ere long a mutual exchange of crab’s 
clothing.” 
M. Bouchard-Chantereaux observes that the shells of Purpura 
lapillus, found on the Boulonnais (France) coast are thinner and 
smaller in those situations where they are subject to the influence 
of brackish or fresh water. It is very fond of Mytilus edulus, 
Mactra, Donax, ete., the shells of which it bores through in from 
three to five minutes, preserving perfect immobility during the 
operation, and protecting the tongue from contact with the sea 
water by applying the two anterior lobes of its foot closely 
around its mouth. After boring the shell of its victim, the 
mantle is torn away, and the viscera only devoured.—Jour. de 
Conch., p. 124, 1879. 
PURPURA (typical). Shell oblong-oval, last whorl large; spire 
generally short; aperture ovate, large with an oblique channel 
or groove at the fore-part ; columella flattened ; outer lip simple. 
PURPURELLA, Dall. Aperture contracted ; outer lip strongly 
dentate within; columella flattened, with one or two distinct 
spiral ridges upon its centre.—P. columellaris, Lam. (xliv, 17). 
TRIBULUS, Klein. Spire depressed, whorls simple, the last ven- 
