





















(ie SOT s)) 
XVIIl.—On some remarkable Marine Invertebrata new to the British Seas. By 
Epwarp Forsss, F.R.S., F.L.S., Professor of Botany, King’s College, London ; 
and J. Goopsir, F.R.S.S.L. and E., Professor of Anatomy, University of Edin- 
burgh. 
(Read 20th January and 3d February 1851.) 
The animals, either wholly new, or new to Britain, described in the following 
communication, were taken during a yachting cruise, with our indefatigable 
friend Mr Macanprew, among the Hebrides, in the month of August 1850. 
During this voyage, which lasted three weeks, a series of observations were con- 
ducted by means of the dredge and the towing-net. Not a single new form of 
testaceous mollusk was procured; our exertions were amply rewarded, however, 
by the discovery of several remarkable Ascidians and Radiata, some of them so 
curious in themselves, and so important in their zoological bearings, that we have 
thought it desirable to lay an account of their characters and anatomy before the 
Royal Society of Edinburgh. 
The most remarkable of them is the largest of compound Ascidians yet dis- 
covered in the Atlantic. Its nearest described ally is the genus Deazona of 
Savieny, between which animal and Clavellina it constitutes a link; one of con- 
siderable zoological importance, since it binds together more closely the truly 
compound Ascidians or Botryllide, with the social Ascidians or Clavellinide, which 
latter in their turn pass into the family of Ascidiade, through the anomalous 
Cynthia aggregata. The discovery of a creature thus filling up a gap in the 
animal series, was of itself a sufficient harvest from our autumn tour; in this 
instance our pleasure was enhanced by the beauty and singularity, as well as 
novelty, of the remarkable animal we have first to describe. 
The SyntEtuys, for so we propose to designate the Ascidian, presents itself 
‘in the form of a compact gelatinous mass of half a foot, and sometimes more in 
diameter, and very nearly an equal height. It is affixed to the rock or stone by 
a short slightly spreading base of various breadth, whence rises as an inverted 
_ pyramid the body of the mass, irregularly circular and slightly lobed, spreading 
out at its summit. It is of a translucent apple-green hue ; the surface is nearly 
smooth. The whole of the expanded disk is thickly studded with individual 
ascidians growing out, as it were, from the common mass. They are arranged in 
irregular rows, with a tendency to concentric order. Each individual measures, 
when full grown, nearly two inches in length, and has the shape of an elongated 
ampulla, with two terminal orifices, set well apart, but not very prominent, and 
VOL. XX. PART II. 40 
