378 The American Naturalist. [May, 
tran, rostrad, caudal, caudan and caudad also work well for the 
remoter parts. All planes lying parallel to any of these within 
the body are distinguished by the prefix “ para.” 
Wilder and Gage have already recommended and now 
habitually use many of the terms also adopted by Schulze, 
but their system was tentative and did not aim at complete- 
ness. They, however, have used effectively “ental” and 
“ectal” terms not noticed by Schulze. Thus “the dura (ma- 
ter)” is “ectad ” of the brain but “entad ” of the cranium. A 
part may be divided by cutting either ecto-entad or ento-ec- 
tad.” There is also another application of words derived from 
ézroe and évtég which seems an obvious advantage. Ectal, 
ectans and ectad can be of great use if limited exclusively to 
parts that protrude from the surface of the body, like the 
appendages in Vertebrata, Crustacea, the spines of Echinoidea, 
the arms of Crinoidea, the tentacles of Actinoza and the like. 
Parts that stand out from the distan or terminan, rostran or 
caudan, dorsan or ventran surfaces of the body. If this were 
done the limbs would all be described as ectal of dextran and 
sinistran surfaces, the articulations of the body would be 
“ectad” or “entad ” of those surfaces or their origin, if pene- 
trating deeper might be designated by an appropriate term 
according to the topical terms already employed, central, 
proximal or distal. All the minor divisions of the ectal parts — 2 
could then be referred to the surfaces of the body. Thus the 
bases of the spine in Echinus would be ectad of the body but 
proximad of its surface, while the termination would be dis- 
tan with relation to the same surface, and it would have its 
own centrum and central region, principal axis, and 80 0n. 
In applying these words to a deeper seated part as to the 
radiating spines of Radiolarian or the threads of the stalk of 
a Hyalonema the use of “ental” to designate the part inside 
of the distan surface of the body would not entail confusion, = 
since it would be used in direct connection with the descrip- 
tion of the spine or threads. The stalk of Hyalonema 
most complicated example would be ental in origin, "a a 
in the distal. It would be better to say the oral or a? io 
rum ane 
. part of the central axis, pass through the cent 
in the 
