374 ScAT.Y Pinna. MOLLUSOA. ^Aviculidas. 
The j'oung shells are very thin and brittle, but some 
of the species, wlien they reach their full size, are thick 
and solid, and attain a length of upwards of two feet. 
The nacreous lining of the interior is thin and scarcely 
extends half-way from the beak. The colour of this 
internal pearly coat is usually of a reddish hue, and 
frequently pearls of a considerable size are found in the 
shells, partaking of the same tint, or that of amber. 
Specimens may be seen in the collection of the British 
Museum. Some of the Pinnas are used as articles of 
food ; while others are valued for the powerful, silky 
byssus which, it has been mentioned, they possess. 
THE SCALY PINNA {Pinna squamosa ) — Plate 11, fig. 
20 — has long been known for the silky material which it 
affords, and which has been woven into various articles 
of dres.s. “ This silk,” says Dr. Johnston, “ is the byssus, 
or rather the cable of the animal, by means of which it 
is moored to the rocks, in the same manner that our 
common mussel is. In a crude state the silk is called 
lanapenna; the threads are extremely fine, of a perfect 
equalness in diameter through their whole length, and 
of great strength. It is clearised from its impurities 
by washing in soap and water, drying, and rubbing 
with the hands. It is then passed through combs of 
bone, and afterwards, for finer purposes, through iron 
combs or cords, so that a pound of the coarse filaments 
is usually reduced to about three ounces of fine thread. 
When mixed with about one-third of real silk, it is 
spun on the distaff, and knit into gloves, caps, stock- 
ings, vests, &c., forming a stuff of a beautiful brownish- 
j'ellow colour (resembling the burnished golden hue on 
the back of certain flies and beetles), blit very liable to 
be moth-eaten, and requiring to be wrapped in fine 
linen. A pair of gloves costs on the spot about six 
shillings, and a pair of stockings eleven ; but its sale is 
not very extensive, and the manufacture is peculiar to 
Toronto.” Specimens of the byssus, and gloves made 
from it, may be seen in the collection of the British 
Museum. It has long been known that a little crab 
infests the mantle or gills of this same Pinna, and in- 
deed the common mussel of our own shores also. The 
fact was known to the ancient naturalists, who, as Dr. 
Johnston observes, “ never left an observation to stand, 
like truth, all naked, but ever clothed it with some 
pretty vestment.” They believed that this little crab 
(belonging to the genus Pinnotheres) formed a close alli- 
ance with the shell-fish, and acted the part of a guar- 
dian to its blind host. The story is told by Pliny, and 
is thus translated by Dr. Holland: — “ The Nacre, also 
called Pinna, is of the kind of shell-fishes. It is alwaies 
found and caught in muddie places, but never without 
a companion, which they call Pinnoter, or Pinnophylax. 
And it is no other but a little shrimpe, or, in some 
places, the smallest crab, which beareth the Nacre 
companie, and waites upon him for to get some vic- 
tuals. The nature of the Nacre is to gape wide, and 
showeth unto the little fishes her seelie body, without 
any eie at all. Tliey come leaping by and by close 
unto her ; and seeing they have good leave, grow so 
hardy and bold as to skip into her shel and fill it ful. 
The shrimp lying iii spiall, seeing this good time and 
opportunitie, giveth token thereof to the Nacre, secretly 
with a little pinch. She hath no sooner this signall 
but she shuts her mouth, and whatsoever was within 
crushes and kills it presently ; and then she divides 
the bootie with the little crab or shrimp, her sentinel 
and companion.” The family Pinnadce isa very natural 
one, and contains only two genera — Pinna, distinguished 
by having the shell elongated and marked with a longi- 
tudinal crack filled with cartilage in the middle of 
each valve ; and Atrina, which has a shorter shell and 
no such crack. 
Family — AVICULIDHH {The Wing-shells). 
The shells are inequivalve, very oblique in most in- 
stances, resting on the right valve, which is the smaller, 
and which has a notch in the front margin for the pas- 
sage of the byssus. The ligament is marginal, and the 
cartilage is contained in one or several grooves, the 
hinge being without teeth, or obscurely dentated. The 
beaks are anterior and eared, the posterior ear wing- 
like. The outer surface of the valves is foliated, with 
an indistinct epidermis, and the interior is highly 
nacredor pearly. There are several genera, as Malleus, 
the Hammer-oyster; the Wing-shell ; Mar- 
garitiphora, the Pearl-oyster ; Perna, and Crenatula — 
but we have only space for a notice of the Pearl-oyster. 
Genus Margaritiphora {the Pearl-oyster). — This 
genus has a less oblique shell than most of the family, 
and the valves are flatter and nearly equal. They are 
somewhat orbicular in shape, and the hinge margin is 
not produced posterlorl}'^ into ears. The hinge is with- 
out teeth, and the ligament is external and dilated in 
the middle. The external surface of the shell is squa- 
mose, and the interior is of a pearly lustre. The Pearl- 
oysters are famed for their production of the beautiful 
Oriental pearl, and the substance, so much used in the 
arts and manufactures, called “ mother of pearl.” The 
shells are found at Ceylon, the Persian Gulf, Mada- 
gascar, the Swan River, Panama, and other parts of 
the coast of America, and are usually procured from 
about twelve fathoms water. Pearls, being amongst 
the most beautiful ornaments for female attire, have for 
a very long time been highly prized, and the love for 
their use has often called down stern denunciations, 
from satirists and moralists, of female vanity. “ Pearls 
of great price” have been eagerly sought after by man- 
kind from the earliest ages. The Romans had an inor- 
dinate love for ornamenting themselves with pearls. 
Pliny tells us that Lollia Paulina (“late wife, and after 
widow, to Gains Caligula, the emperor,”) used to wear 
such a quantity of pearls and emeralds about her person, 
that the value was rated, according to her own estima- 
tion, at 400,000 sestertii. “ I have seen her,” he says, 
“ so beset and bedeckt all over with hemeraulds and 
pearls, disposed in rows, ranks, and courses one by 
another ; round about the attire of her head, her cowle, 
her borders, her peruk of hair, her bond grace and 
chaplet ; at her eares pendant, about her neck in a car- 
canet, upon her wrist in bracelets, and on her fingers 
in rings ; that she glittered and shone again like the sun 
as she went.” In those days the most extravagant 
prices were given for pearls. Julius Caesar, we are 
told, presented Servilia, the mother of M. Brutus, with 
a pearl worth £48,417 ; and the celebrated Cleopatra, 
