D A C 
i^iifi be funk within three inches of the bottonn. 
The winter-fifhing for Dace requires very diffe- 
rent baits ; namely, thofe white, red-headed mag- 
gots, ufually found in great numbers in ploughed 
lands, and which, if depofited among frefh earth, 
may be preferved many months for that purpofe. 
Dace are extremely vivacious ; and, when im- 
merfed in water, will live a confiderable time, pro- 
vided that element is frequently changed. They 
are faid to fubfift on the animalcula found in the 
Water; and, in time, to become extremely tame. 
DACOLYTHUS. An appellation given by 
many authors to a fmall fifli, a fpecies of the loach, 
diftinguifhed by Ray under the name of cobitis 
barbatula aculeata. It feldom exceeds two, or at 
moft three, inches in length; the head is broader 
and flatter than the reft of the body; the back is 
of a dufky brown colour, fpotted with black ; and 
the belly is yellow. There are two beards on each 
fide of the upper-jaw; and on the coverings of the 
gills, on both fides, there are two prickles, or a 
double-pointed fharphook, by means of which the 
Dacolythus moves about among the ftones. This 
filhi, which is very partial to fliallov/ waters with 
fbony bottoms, fpawns in May and June. 
There is another fpecies of this fifh, diftinguiflied 
from the preceding by having ten beards at it's 
mouth : and a notion prevails among the vulgar, 
that it fwallows little ftones ; hence it's German 
appellation fignifies Stone-fwallower, orStone-biter. 
DACTYL, A name frequently given to the 
folen, or razor-fifti, fuppofed to be the Daftylus of 
Pliny, and to which that naturalift afcribcs a lu- 
minous quality in the dark. Reaumur, however, 
aflerts, that the common foal or razor-fifli pof- 
feffes no fuch quality; but that the pholas, or, as 
the French call it, the dail, certainly does; and 
therefore concludes, that the pholas is eitlier the 
Daclylus of Pliny, or that this author has attributed 
to one fpecies of fifli what is the peculiar property 
of another. 
The ftiell of the Da(5lyl, or pholas, is by no 
means luminous, but only it's body and juices ; 
and in this refpeft it bears no affinity to fome kinds 
of fifti which are known to poffefs the quality of 
ihining in the dark, fince thefe never exhibit a lu- 
minous appearance till they are in a ftate of de- 
cay, and partly putrid; whereas thofe retain their 
reiplendent quality at all times. The glow-worm 
is only partially luminous; but the pholas is en- 
tirely fo; and, when divefted of it's ftiell, and de- 
pofited in any dark place, every part of it's fvir- 
face emits a very lively light. Nor is that light 
peculiar to the external furface of this fifli, but 
common to the whole body; for, when wounded 
either tranfverfely or longitudinally, the mangled 
parts appear equally luminous with the other fur- 
faces. The Da£lyl is therefore a genuine, natural 
phofphorus; and, like the artificial one of urine, 
renders every obje6l luminous by fri6lion. 
Reaumur has remarked of this fifli, that, when 
frefti caught, it abounds with water, which natu- 
rally drops away on being handled ; and, accord- 
ing to Pliny's juft obfervation, thefe very drops are 
luminous. However, the light which the Daftyl 
communicates to bodies coming in conta6t with it, 
is not permanent, but continues only while they 
are wet. Reaumur obferved that the light on his 
fingers grew fainter and fainter by degrees as they 
dried ; and that, on dipping them in water, it 
brightened up again. By this circumftance, he 
was encouraged to atten:ipt fome mode of pre- 
DAN 
ferving this fifli, fo as to make it an occafiona! 
phofphorus, but the experiment did not coincide; 
with his wiflies. 
In the fummer months Da6lyls may be kept 
frefh for feveral days, during which they will retain' ' 
their luminous quality; but, as they begin to de- 
cay, they gradually lofe their luftre: and it alfo ap- 
pears that, if dead ones are intermixed with living, 
the latter will lofe their luminous quality even in- 
their beft ftate. 
It is well known that all the fpecies of the pholas 
live in holes in ftones and other fubftances, where 
they have no egrefs ; and Reaumur having caufed 
fome of thefe ftones to be taken up, (in which, on 
breaking them, there appeared fome dead fifli, and 
fome living ones) difcovered, that the living ani- 
mals contained in them did not pofl'efs their lumi- 
nous property, but that it feemed to be extinguilhed 
by having been in contaft with fuch of the pholse 
as were dead and putrid. 
DAGYSA. A marine animal found within 
twenty leagues of the coaft of Spain, and firft no- 
ticed by Sir Jofeph Banks and Dr. Solander, who 
gave the name of Dagyfa to this new genus of ma- 
rine animals becaufe of the refemblance which one 
fpecies of them bore to a gem. This creature, 
which was of an angular figure, about three inches 
long and one thick, had a perforation quite through 
it, and a brown fpot at one extremity, which thefe 
gentlemen conjeftured to be the ftomach. Four 
of thefe animals, when firft taken, adhered together 
by their fides, and appeared to be only one; bur, 
on being put into a giafs of water, they foon fepa- 
rated, and fwam about. Several fpecimens of 
tliem were afterwards caught ftickino; tos-ether, 
fometimes to the length of a yard or more ; and, 
when in the water, exhibiting very beautiful co- 
lours. 
DAKER HEN. The Englifli name for the 
ortygometra, a bird of the gallinaceous kind fome- 
what refembling the quail. It weighs about four 
ounces and a half; it's length, from the tip of the 
bill to the end of the claws, is fifteen inches, and 
to the end of the tail eleven inches and a halfj 
the expanfion of the wings is nine inches; the body 
is narrow, or compreflTed fideways like that of the ~ 
water-hen; the breaft and belly are white; on the 
head there are two broad black lines; and there is 
likewife a white one which runs from the fcapulars, 
as in the moor-hen. The back is black, with an 
admixture of reddifli afli-colour; and the leffer co- 
verts of the wings, as well as the borders of the 
prime-feathers, arc of a deep yellow. The tail is 
two inches long; the bill is of a moderate fize; and 
the legs and feet, which are long, are between a 
faffron and a green colour. 
The Daker Hen refembles the quail in many 
refpefts, and is faid to aflx)C!ate with one fpecies 
of quails. During the fpring, it frequents corn- 
fielcis, and puts forth a croaking call very peculiar 
to itfelf, which fowlers fometim.es imitate with much 
fuccefs. It is very common in Ireland and Scot- 
land ; and is fometimes feen in the northern coun - 
ties of En.gland, where it is known under various 
appellations. 
DiVMIER. A name given by French na- 
turalifts to that elegant fpecies of voluta, the fpots- 
of whicli are placed in a chequered order, refem- 
bling the marks of a draught oi" chefs-board. 
DANCER. An appellation fometimes givea 
to a fpecies of the dog. 
DANGCANGHAC. The Philippine name 
for 
