Anatomical Nomenclature of Echinoderms. 17 
strict sense in which the term is to be used for the future 
should surely be that in which it was most generally used in 
the past. This is very far from being the case with Lov&i’s 
specialization of the term costals, as will be seen from the 
preceding table ; and as his proposal has not been generally 
adopted by Echinologists, I think there can be no harm in 
employing Miller’s name for plates which do lie in the 
direction of the rays of Crinoids, and were always called 
costals by him when not described as arm-plates, viz. those 
commonly known as the second radials. This being granted, 
it naturally follows that the axillary or third radials, the 
scapulae of Miller, should be called the second costals; and 
these terms will be employed for the future by Messrs. 
Wachsmuth and Springer, Bather, and myself. Further- 
more, in genera like Metacrinus and Parisocrinus , in which 
there may be four or five joints between the radial and the 
first axillary above it, the whole series, including the axillary, 
will in future be called the costals. 
The use of this term also simplifies matters in another way. 
I pointed out in 1877 *, and have done so frequently since, 
that the first two joints beyond every axillary of a multi- 
brachiate Neocrinoid are nearly always united, whether by 
syzygy or by bifascial articulation, in the same manner as the 
second and third radials. Now, however, we can say more 
briefly that there is generally the same mode of union between 
the first two free brachials and the first two distichals and 
palmars &c., when present, as between the first two costals. 
Thus, among the Pakeocrinoidea this union is a syzygy in 
Graphiocrinus and Scytalocrinus . The same rule holds good 
in Encrinus (syzygy) and in Apiocrinus , Miller icrinus, and 
Bathycrinus (articulation). Five of the eight recent species 
of Pentacrinus have the two costals, distichals, and palmars, 
and the first two free brachials respectively united by syzygy, 
while there are bifascial articulations between the two costals 
and the first pair of joints beyond them in each of the other 
three species. Some of the fossil Pentacrinidae present indi- 
cations of the same regularity, and it is also traceable in Meta - 
crinuSy though to a less extent, owing to its larger and more 
variable number of costals ; and this is probably also the case 
in the Pakeocrinoids with a similar character. 
It is among the Gomatulce , however, that the regularity in 
question is most marked. Among the 120 species of Antedon 
* u On the Genus Actinometra , Miill., with a Morphological Account 
of a new Species from the Philippine Islands,” Trans. Linn. Soc., 2nd ser. 
Zool. vol. ii. p. 22. 
Ann. & May. N. Hist , Ser. 6. Vol. vi. 
2 
