Terms in Crinotd Morphology. 53 
Brachials =all arm-ossicles, or, in other words, all ossicles 
situated in the direction of the rays, distal to the 
radial (s. str.) and belonging to the abactinal system. 
Costals =the first order of brachials, 7. e. all brachials from 
the radial up to and including the first axillary. 
Distichals=the second order of brachials. 
Palmars =the third order of brachials. 
First Postpalmars=the fourth order of brachials. 
Second Postpalmars=the fifth order of brachials; and so on. 
Free Brachials=all brachials after the last axillary, which- 
ever that axillary may be. 
Through the kindness of Dr. Carpenter I had already been 
- able to put forward the above terminology * and to announce 
that it would be used in my papers on British Fossil Crinoids. 
Wachsmuth and Springer had also privately expressed their 
intention of accepting it. The latter authors, however, have 
already found it necessary to modify it slightly ¢. ‘‘ To the 
most of this terminology,” they say, ‘‘ we entirely agreed, but 
in some particulars it does not quite meet the requirement in 
dealing with the greater complexity and variety of construc- 
tion found in the Paleozoic forms.” Instead of applying the 
term Mree Brachials to brachials after the last axillary only, 
they use it in a different and extended sense, applying it to 
all brachials that are free from the calyx, as are all the arm- 
ossicles in the Inadunata. The term is thus opposed to Fixed 
Brachials, by which is meant those arm-ossicles incorporated 
in the calyx, such as are often found in the Camerata. 
In the same place Wachsmuth and Springer have supple- 
mented the above terminology, as follows :— 
“Interradials, all plates interradially disposed in the calyx. 
“Interbrachials, a general term for all plates between the rays 
: above the radials. 
“Interdistichals, the plates between the first divisions of the 
ray. 
“Interpalmars, those between the second divisions of the ray. 
““Interambulacrals, the plates between the ambulacra.” 
In applying to Paleozoic Crinoids the terminology to which 
I stood committed, I soon stumbled on certain difficulties. 
‘his was especially the case in the attempt to work out and 
* Brit, Foss, Crin., II.,” Ann. & Mag. Nat. Hist. (6) vol. v. p. 318, 
April 1890. 
t “The Perisomic Plates of the Crinoids,” Proc. Acad. Nat. Sci. 
Philadelphia, vol. for 1890, p. 374: Feb. 1891. 
