1882. | CLASSIFICATION OF THE COMATULA, 735 
the former loses its pinnule. No Crinoid with three radials ever 
has a pinnule on the second one; and when this becomes the hypo- 
zygal of a syzygy, it does not therefore lose its individuality, as is 
the case with the hypozygals of the brachial syzygies. Almost the 
same may be said respecting the first two brachials. Most Comatule 
have a syzygy in the third brachial with a bifascial articulation be- 
tween the two preceding joints, the second only of which bears a 
pinnule. Hence where these two are united by syzygy, as in Act. 
solaris, the first or hypozygal loses no individuality as an arm- 
joint. They are therefore better described as the first and second 
brachials, and not as a first brachial which “is a syzygy.’ This 
method has the advantage of retaining the third brachial as a syzy- 
gial joint as a condition which is common to by far the larger num- 
ber of Comatule ; for it is only a very few species, like Act. fimbriata 
and Act. multiradiata, which have a syzygy in the second brachial 
and a pinnule on the first. This is an entirely different type, and 
arises from the coalescence of the primitive second and third joints of 
the growing arm. 
I cannot, therefore, regard as satisfactory Prof. Bell’s formule for 
Act. solaris, Act. brachiolata, e. g. 1.2.A'R h and 1.2.A’R PB. For 
the radial axillary is not a syzygy in the same sense as the distichal 
axillary is in Act. parvicirra; neither is the first brachial a syzygy 
in the same sense as the second or, as I should call it, the third. 
I am bound to say, however, that I am in some measure respon- 
sible in the matter of the first brachials, having employed this mode 
of description in my diagnoses of the Leyden Comatule’; but since 
then I have decided to abandon it, as will be seen from my descrip- 
tions of Act. solaris and Act. robusta of the Hamburg Museum, to 
to which I have added a few of my reasons for the change’. 
The erroneous character of some of the formule given by Prof. 
Bell is due, I fear, to his not having properly understood the de- 
scriptive terminology which I have been led to employ. I have 
endeavoured, as much as possible, to make it simply an extension of 
that used by Miiller; and I have consequeutly used the word “rays” 
in the same sense as Miiller did, as I have pointed out above ®. 
Prof. Bell, however, seems not only to use it in a different sense him- 
self, but also to have understood me as doing so. The result is that 
many of the formule which he has drawn up on the basis of my 
descriptions are utterly at variance with them. 
The following is an abbreviated extract from the classification of 
the species of Actinometra in the Leyden Museum, together with the 
formule assigned to those species by Prof. Bell :— 
A. Second and third radials united by syzygy. 
cay? Ber QMS Mes BSS solaris. 1.2.A'RP. 
(. Many arms. Rays may divide five times or more. First 
' Notes from the Leyden Museum, vol. iii. pp. 170-217. 
2 «The Comatule of the Hamburg Museum,” Journ. Linn. Soe, Zoology, vol. 
xvi. pp. 514-519. 
3 P. 732, note. 
Proc. Zoou. Soc.—1882, No. XLIX,. 49 
