THE PYROSOMA . 
359 
which the creature sways like a fritillary on its slender stalk. The two orifices by which 
water is admitted into and ejected from the system are seen, and their remarkable four-cleft 
openings are well displayed. When very young, the Boltenia is often found affixed to the 
stem of its parent. 
The Boltenia, several species, is an unfamiliar animal, unless the observer is interested 
enough to go to the .beaches after storms, when it will be found cast ashore, with great 
quantities of sea-weeds, kelp, etc. It is always an attractive creature, looking more like a 
rich peach or damson, with its beautiful pink and lemon coloration. 
Many of the Ascidians are very uninviting in appearance. 
The Cynthia pyrieformis is one of the most beautiful of the race. It is called Sea-Peach, 
from its rich velvety surface and bright pink blush, precisely the aspect of a blood-peach. 
We now arrive at the Social Ascidians. Our first example of them is the Clavellina. 
Its blood circulates through channels of communication, passing to and fro through separate 
tubes. It is a small creature, and extremely transparent, the latter characteristic making it a 
valuable species to the physiologist, who is enabled to watch its structure, and the methods in 
which the different organs perform their duties, without needing to dissect it. The Clavellina 
may be found on the European shores at low water, adherent to rocks, stones, or sea- weed, to 
which it attaches itself by means of the tiny root-like projections which are developed from 
the outer tunic, something like the little rootlets by which ivy clings to a wall. 
Our second example is the Syhtethys, another European species. When full-grown, a 
group of these creatures forms a largish mass, nearly six inches in diameter, and as many in 
height, each member of the group being about two inches long. They are rather transparent 
and of a greenish color, and, when touched, they will contract themselves violently, and 
vanish into the common mass on which they are seated. These animals are propagated both 
by eggs and buds, the buds being produced on offshoots of the creeping tube. Sometimes the 
young one severs its connection with the parent, and fixes upon some fresh locality, there to 
form the basis of a new colony, but it frequently remains on the same spot, and only serves to 
increase the general mass. 
Of the Botryllidse, or Compound Ascidians, we may mention the common Star-shaped 
Botryllus. The “tests,” or equivalents of the shell of these animals, are fused into a 
common mass in which these individuals are imbedded. In the present genus the animals 
are arranged in a star-like form, each group consisting of a number of individuals, not less 
than six, and not more than twenty, in number. Many of these groups, or systems as they 
are technically called, are found upon the common test. The branchial orifices are simple, and 
the other orifice is common to all the members of the group, and forms, as it were, the centre 
of the radiating star. Six European species are known, which may be found on stones and 
sea- weed at low- water mark. 
Avery beautiful and curious mollusk, called from its luminous appearance the Pyrosoma, 
i. e . , Fire-body, is an example of the next family. This is one of the compound tuni cates, and 
looks like a gelatinous cylinder, open at one end, and closed at the other, and having its body 
covered with numerous zoids grouped in whorls. A large Italian-iron tube, studded with 
daisies, will give a good idea of its general shape. 
The ejecting orifices of the aggregated animals all open into the hollow interior of the 
cylinder, and the consequence of this structure is, that by the constant flow of the rejected 
water, the whole mass is driven slowly and regularly through the waves. When seen at night 
they look just as if they were made of glowing white-hot iron, and they are at times so 
numerous as to choke up the nets of the fishermen, and diffuse so strong a light around them 
that even the fishes are rendered visible when they happen to swim within the sphere of its 
radiance. There is generally a greenish hue about the light. 
Of the appearance presented by these animals when existing in great numbers, Mr. F. D. 
Bennett gives the following vivid and valuable account : “ When assembled in the sea. and, as 
