18 
Dr. P. H. Carpenter on the 
noticed in the c Challenger ’ Report there are but nine in 
which the first two joints beyond each successive axillary are 
not always united in the same manner as the two costals are. 
Thus in the three members of the Elegans-gvouip the costals 
are united by syzygy, while the first two joints after each 
axillary are articulated. In the six members of the Granu- 
lifera-g roup the costals and the first two distichals are articu- 
lated bifascially. Five of the species have the corresponding 
palmars and brachials united by syzygy, while in the sixth 
this is replaced by a muscular articulation. 
Among the eighty-four species of Actinometra the four 
members of the Typica - group have a syzygy between the two 
costals, palmars, postpalmars, and brachials respectively, while 
the first two distichals are articulated ; and in the seven 
species of the Fimbriata- group the costals and the first pair 
of distichals are respectively united bifascially, while there 
is a muscular articulation between the first two joints after 
the distichal and all subsequent axillaries. The four members 
of the Stelligera-fri'oxrp again have the first two free brachials 
united by syzygy, while the corresponding joints of all the 
lower arm-divisions are articulated. 
Excepting in these aberrant forms, therefore, the facts of 
Crinoid anatomy are in favour of the view that the plates 
called second and third radials by Muller really belong to the 
arms; and so I propose to abandon the use of R in the specific 
formulae of the Elegaiis -, Solaris-y and Typica-grovaps* , and to 
substitute a c, indicating the costals, just as d stands for 
distichals and p for palmars. A glance of the illustrative 
formulae given below, and especially those of Actinometra 
Solaris and A. paucieirra , will show that this alteration makes 
them at once more simple and more symmetrical ; and as it 
seems undesirable to have one c in the formulae to indicate 
costals and another in the cirrus-notation, as proposed by 
Bell 1 propose to use a?, 3 /, z tor the latter purpose instead 
of a, b y c . This has the further advantage of enabling us to 
write a simple by and not br : to indicate the free brachials of 
the arms. 
* See the Report od the i Challenger ' Comatuhe , pp. 53, 57. 
t “ An Attempt to apply a Method of Formulation to the Species of 
the Comatulidce, with the Description of a new Species,” Proc. Zool. Soc. 
Lond. 1882, p. 531. See also the Report on the ‘ Challenger ’ Comotulce 
pp. 43-59. 
