AND DEVELOPMENT OE MYRIOTHELA. 
551 
and was totally mistaken as to its affinities, while Saks, evidently unaware that the animal 
had been previously noticed, had an accurate conception of its true zoological relations, 
the name of Myriothela may fairly be accepted without any violation of the spirit which 
ought to regulate biological nomenclature. And though no less an authority than Prof. 
Louis Agassiz has felt himself compelled to restore De Blainville’s name, I believe that 
farther confusion will be avoided, and no injustice done, by adopting the later designa- 
tion of the genus. 
It is quite possible that the existing accounts of Myriothela include more than one 
species. At present, however, we have no evidence which would satisfy us in asserting 
that more than a single species has been observed ; and the specific name assigned by 
Fabricius to the first known example of the genus must accordingly be accepted. 
Sars’s description is entirely confined to the external characters of the adult ; and the 
first account which takes us beyond these is given by Mr. Cocks*, who describes the 
young locomotive stage which he saw developed from specimens obtained on the coast 
of Cornwall. Mr. Cocks’s observation has been confirmed by Mr. Alder, who, however, 
has left us no published account. Mr. Hikcks, from an observation of living specimens, 
has given us an excellent description of the external characters of the adult, and has 
correctly pointed out the true composition of the colony, maintaining the zooidal signi- 
ficance of the appendages which support the gonophoresf. 
The only other notices we possess are a short one by Mr. Vigors J, who, not aware of 
the previous descriptions by Fabricius and Saks, records the animal under the new 
generic and specific names of Arum CocJcsii ; and one by Mr. Gosse §, who also describes 
it as a new genus and species, under the name of Spadix purpurea. 
The only published figures are one accompanying Mr. Cocks’s description of the 
locomotive stage, a small woodcut outline by Mr. Gosse, and a characteristic figure by 
Mr. Hincks. 
The specimens which have afforded the material for the present memoir were obtained 
at Lulworth, on the coast of Dorsetshire. They were attached to the under surface of 
large stones, close to the low-water level of spring-tides. 
ANATOMY. 
The Trophosome. — Structure op Hydranth. 
1. Endoderm. 
The character of the endoderm varies according to the region in which it is examined. 
Throughout the whole of the main cavity of the body it constitutes a thick layer, composed 
of many cells in depth (Plate 56. figs. 1 & 2, a). The cells which form the greater part 
of this endodermal layer consist of simple round masses of clear protoplasm, about 
of an inch in diameter, in which a nucleus is frequently visible, and in which are immersed 
* Rep. of Roy. Pol. Soc. Cornwall, 1853, p. 34. t Rep. Roy. Pol. Soe. Cornwall, 4849. ' 5 ’ 
t Brit. Zooph. 1868, p. 75. § Ann. Nat. Hist. 1853, and Man. of Marine Zoology, 1855, 
4 D 2 
