Part IT.—Stichodactyline and Zoanthee. 137 
coloured from all the rest. They are all, however, on the same radii as the inner 
rows, which are not cyclic. 
In Actinoporus the tentacles are simple or lobed vesicles, are practically all 
alike, and occupy all the radial divisions, two or more irregular rows com- 
municating with the same mesenterial chamber. 
Where the tentacles are so crowded, some of these relationships and 
distinctions are not easily recognized in contracted, preserved specimens. In 
living polyps, they can more readily be made out, often facilitated by colour 
distinctions. 
I think it is desirable to have some division expressive of the similarity, or 
otherwise, of the tentacles in any genus, and therefore propose the following 
Sub-orders :— 
HETERODACTYLINE. 
Stichodactylinze, in which the tentacles are of two forms, usually marginal 
and accessory, and separated by a naked portion of the disc. Lvamples—Phy- 
manthus, Actinotryx, Rhodactis, Cryptodendron, Heterodactyla. 
HoMoDACTYLINZ. 
Stichodactylinze, in which the tentacles are all of one kind, simple or complex, 
and usually follow one another in continuous rows. Lxvamples—Discosoma, 
Ricordea, Stoichactis, Radianthus, Corynactis, Homostichanthus, Actinoporus. 
Generally the more central tentacles are smaller or less complex than the 
more peripheral, but within the same species they are all formed on one plan. 
Dr. Carlgren (1891, 1893) has erected the tribe Protanthese, of which the most 
salient character is that the column-wall and stomodzum possess an ectodermal 
ganglion and longitudinal muscle layer. First formed to include the genera 
Gonactinia and Protanthea, in his later paper he embraces Thawmactis 
medusoides, Fowler, and the genera Corynactis and Corallimorphus, re- 
presenting the families Thaumactinide and Corallimorphide respectively. 
Thaumactis has since been shown by Professor Haddon and myself (1896, 
p. 158) to be included in the family Aliciide, and I do not consider the presence 
of an ectodermal musculature of sufficient importance to warrant the separation 
of the Corallimorphide from its more natural place among the Stichodactyline. 
A columnar and stomodzal ectodermal musculature and nerve layer are now 
known for many Hexactiniz, the other characters of which indicate that they belong 
to totally different families. Professor M*Murrich (1893, p. 148) refers to the 
probable occurrence of an ectodermal musculature in Haleurias pilatus; I have 
recorded it (1897) in two species of Bunodeopsis, and describe its presence in 
