1882. | CLASSIFICATION OF THE COMATUL2, 743 
The want of elasticity which renders Prof. Bell’s system so mis- 
leading will not be found, I hope, in that which I am now about to 
explain. It has grown up gradually during seven years’ work, and 
will meet all the variations of actual Comatula-structure with which 
I am acquainted, together with any others that I can imagine as 
possible. Some time ago I pointed out that “the first and second 
segments beyond every axillary, whether radial or brachial, are 
nearly always united together in the same manner as the second and 
third (axillary) radials.” Further experience has shown that the 
“nearly”? embraces several well-marked but regular exceptions to 
the above statement ; and I have therefore drawn up the following 
rules, which embody the results of my study of the group. They 
are not to be in any way regarded as laws of Comatula-structure, 
but merely as generalizations based upon a knowledge of some 
400 species, and therefore, I hope, of some value for the purpose of 
classification. : 
1. All ten-armed species of Actinometra which have the two 
outer radials united by syzygy, have the first two brachials united 
in the same way. 
Ex. Act. solaris. No Antedon known. 
2. All many-armed species of Actinometra which have the outer 
radials united by syzygy either have (a) all the ray-divisions of two 
joints also united by syzygy and the first two brachials similarly 
united ; or (3) there may be three distichals, of which the first two 
are articulated and the axillary is a syzygy, while the subsequent 
divisions are as above. 
Ex. a. Act. jukesi; B. Act. typica. 
3. If the two outer radials are united by a ligamentous articu- 
tion, the next two joints are similarly united, whether there be ten 
or many arms. In the former case the third brachial is almost 
always a syzygy. (One of the “ Blake” Comatule is an exception.) 
Ex. Ant. rosacea, Ant. philiberti, Act. meridionalis, Act. 
parvicirra. 
4, In by far the greater number of Comatule which have the 
two outer radials articulated by ligaments and only two ray-divisions, 
the third brachial is the lowest syzygial joint on the arms, whether 
the distichal axillary be a syzygy or not; and the two lowest 
brachials are articulated by ligaments. 
Ex. Ant. macronema, Ant. reynaudi, Act. trichoptera. 
Exceptions. dct. fimbriata and Act. borneensis, with some unde- 
scribed Antedon-species, have the second brachial a syzygy, like the 
distichal axillary. Act. pulchella and a new ‘ Challenger’ Antedon 
have two distichals the axillary not a syzygy, but the first two 
brachials united by syzygy. 
5. If the two outer radials are articulated and there are more than 
two ray-divisions, so that palmars are present, the third brachial is 
the first arm-syzygy in all cases but the following :— 
a. Two palmars united by syzygy ; the first two joints beyond 
the palmar and all subsequent axillaries are also united by 
BY2YEY- 
