cclxxviii 
DiscoPHOEiE . RAD I AT A. Hydeoids. 
found cast on tlie beaclies. 'I’liey are tough compar- 
atively — some seem almost like cartilage — yet, when 
dried in the sun, they leave a mere film, hardly dis- 
cernible. A specimen weighing about thirty-four 
pounds lost ninety-nine per cent, of its original weight 
after exposure to the sun. 'I’he Discophores are dis- 
tinguished by their peculiar reproductive organs. 
'I'hese are arranged in pouches, and, when spawning 
takes place, the eggs are discharged into the stomach, 
and through it out of the mouth. 'I'he nutritive tubes 
form a net-work near the periphery more complicated 
than the simple circular tube of the Hydroids. See 
Acalephm, Plate 2, figs. 1, 3, 4, 5, 6. 
CYANEA {G. arctica). — 'I’hisis the largest and most 
familiar species of Jelly-fish on our shores. The ten- 
tacles are numerous, rising in eight distinct trunks 
from the margin of the body, and hanging below in a 
maze of slimy entangled feelers. Behind the veil of 
tentacles, and partly hidden by it, are four curtain- 
like appendages, lobed and ruffled on their margins, 
hanging down from the under surface. The ovaries 
are contained in four pendant pouches near the mouth, 
and are connected with four cavities within the body. 
Eight eye-specks are situated on the periphery of the 
body ; each of these is a small tube placed under a 
protecting prominence upon the upper side of the 
disk. 'I’his Jelly is usually of a brownish-red, often 
of lighter shades, with a light creamy-colored margin, 
slightly tinged with blue. 
Madame Agassiz, describing a specimen seen neai’ 
Egg Rock, Nahant, of such magnitude that it is well 
entitled to be held as of historic interest, saj^s : 
“ Encountering one of these huge Jelly-fishes one day, 
when out in a row-boat, we attempted to make a 
rough measurement of its dimensions on the spot. 
He was lying quietly near the surface, and did not 
seem in the least disturbed by the proceeding, but 
allowed the oar — eight feet in length — to be laid 
across the disk, which proved to be about seven feet 
in diameter. Backing the boat slowly along the line 
of the tentacles, which were floating at their utmost 
extension behind him, we then measured these in the 
same manner, and found them to be rather more than 
fourteen times the length of the oar, thus covering a 
space of some hundred and twelve feet. 'I'liis sounds 
so marvellous that it may be taken as an exaggera- 
tion ; but though such an estimate could not of course 
be absolutely accurate, yet the facts are rather under- 
stated than over-stated, in the dimensions here given. 
And, indeed, the observation was more careful and 
precise than the circumstances would lead one to 
suppose, for the creature lay as quietly while his 
measure was taken as if he had intended to give 
every facility for the o])eration. 'J'his specimen was, 
however, of unusual size; they more commonly meas- 
ure from three to four feet across the disk, while the 
tentacles may be thirty or forty feet long.” We may 
well regard such a huge form with caution and dread, 
as these animals have the stinging apparatus, which 
in some species is so potent as to produce death when 
brought in contact with some large Pishes. 
AURELIA (A. flavidula). — 'I'his is seen in many 
sizes, reaching the diameter of fifteen inches. It is 
nearly colorless and transparent, and decomposes so 
readily when thrown on shore that it escapes partic- 
ular notice. At times the surface of the sea is fairly 
occupied by individuals of the species, and hence it 
is more commonly known to those who ‘-go down to 
the sea in ships.” 
CAMPANELLA (G. pachyderma). — 'I'his interest- 
ing and diminutive creature shows a marked con- 
trast in its dimensions compared with the forms 
])receding, being no larger than a pin’s head. It is a 
direct jiroduct of the egg, without passing through 
any other phases of life. 
CIRCE {Traehynema digitale) is a bell-shaped form, 
about an inch in length, having a cone-like termina- 
tion at the upper extremity. It is hard and horny to 
the touch, the veil being a thick-folded membrane; 
the body is a delicate rose-color. 
LUCERNARIA [Halyclktus auricula), found on 
the Eel-grass on our northern shores, is of a flaring 
bell-shape, with a stem-like process at the top, by 
which it attaches itself to sea-weeds. It is free, how- 
ever, to float or propel through the water. 'I’he 
color is aquamarine, varied in some by a tinge of red 
or brown. Its tough membraneous consistence gives 
it an aspect different from the ideal Jelly-fish, and 
more like the Actinias or Sea-anemones. 
HYDROIDS. 
'I'his order includes the lowest forms oi Acalephm ; 
those which early in life attached themselves to ma- 
rine objects by a stalk like a cluster of vegetation, or 
are permanently so situated. Hydroids put forth 
upon their stalks, buds which grow to be Jelly-fi.shes, 
and these break off in some instances to become IVee- 
swimming animals, while others remain permanently 
on the parent stalk. 'I'he process called “alternate 
generation ” is here seen : the buds of the Hydroids, 
whether free or fixed, produce eggs in their turn, and 
perpetuate this remarkable cycle of existence. 
Recent investigation has ascertained that the Mil- 
lepore, so abundantly associated with the Corals of 
the Florida and other Reefs, is a Hydroid Acaleph. 
'I’his discovery proves that these Jellies lived in early 
aeological times ; and a large number of fossil Corals 
are now enumerated as the solid parts nl Acalephs or 
Hydroid Polyps. With the exception of those form- 
ing Coral masses, such as the Millepore, iZyJroiJs 
are short-lived. Polyps proper live many years ; and 
Star-fishes and Sea-urchins require ten or fifteen years 
to attain full size. 'I’he Acalephs complete all their 
changes and their existence in one year. Breedimr 
in the autumn, the eggs grow to be Hydroids during 
the winter; in the spring the Jelly-fish is free from 
the Hydroid stalk, or developed upon it ; in the Cali it 
I'eaches its lull growth and is an adult animal, dying 
and floating iq)on the shore after having cast forth 
its store of eggs. Hydroids are divided into eight 
sub-orders, forty-six families, and about one hnndred 
and thirty genera. 
EUCOPE {^Eucopc diaphana). — 'I’his is a delicate 
little Jelly-fish, and one of the most common and 
beautiful on our shores. Nothing in microscopy is 
