738 MR. P. H. CARPENTER ON THE [Dec. 19, 
veniently described as consisting of distichal joints. But in order 
to avoid misconception, I expressly inserted the word distichals in 
speaking of the first division of the rays of Act. pulchella'. The 
description of this species was written before those of the Leyden 
Comatule, and must have been read by Prof. Bell, as he gives a for- 
mula based upon it. 
I cannot help suspecting, however, from the formula which he 
gives for Act. alternans, that he has thus misunderstood my meaning. 
It is as follows, 3A’RPP’°. This can only be interpreted in the 
following way :—that the radial axillary “isa syzygy ” (which is not 
the case); that there are two distichals’, the axillary without a syzygy 
(while there are really three, the axillary with a syzygy) ; that there 
are two or three palmars, the axillary with a syzygy (while there are 
really two, the axillary without a syzygy) ; and so on for the two re- 
maining divisions, so that the formula should read 3 A'DP'P!"?. Even 
then, however, it would not indicate whether two or three distichals 
are present*, nor whether there are one or two palmars, nor the 
number of joints in the two remaining divisions ; so that one would 
be entirely at a loss as to the systematic position of the type. 
Prof. Bell gives the formula for Act. japonica as /3 A'R ; Even 
after the removal of the unnecessary and totally misleading R, the 
formula is entirely incorrect as regards the ray-divisions, and says 
nothing about any palmars being present. It means that there are 
two distichals, the axillary not a syzygy- But in Miiller’s classifi- 
cation this species is placed in a group distinguished as follows, 
“Die Axillaria der Arme mit Syzygien;”’ and my own description 
runs, “ Primary and secondary arms each of three joints, the axillary 
a syzygy,” or, as Prof. Bell puts it, “Three distichals and three 
palmars, the axillaries syzygies.” His formula should therefore 
be 3A'DP 5. 
The formula which he gives for Act. parvicirra (3 A'DP ®) 
implies that palmars are always present on some of the rays. A 
specimen has been figured, however, with 13 arms only, having 
distichals on only three rays and no palmars at all ; and others have 
been noticed with but 18 and 20 arms*. The P should therefore be 
put within brackets, and the formula stand 3 A'D(P) ey like that of 
Act. wahlbergi, Miill., and Act. variabilis, Bell, MS. 
In like manner the formula given for Act. peroni (3 A'RDP 2) 
does not convey the information that there may be another axillary 
Bull. Mus.-Comp. Zool. vol. ix. no. 4, p. 10. 
> Tam ata loss to understand how Prof. Bell can have supposed that the 
second joint after the radial axillary, which is described as bearing a pinnule, 
can at the same time be an axillary joint ; but no other types without a syzygy 
in the axillary than a series of two distichals have yet been described. 
5 J.e, unless the rule be known that if the distichal axillary is a syzygy it is 
always the third joint, and not the second, as may sometimes be the case with 
the palmars. 
* Trans. Linn. Soe. 2nd series, Zool. vol. ii. 1879, p. 44, and pl. ii. fig. 9. 
