XVI 
THE VOYAGE OE H.M.S. CHALLENGER. 
Explanation of Teems. 
Subjoined are a few notes respecting some of the terms employed in this Report, 
which may perhaps require explanation either as new or as employed in a particular 
sense. 
I. With respect to the characters presented by the Zoarium, I have employed the 
word dimorphous to express that it may be both erect or free, or decurrent and incrusting, 
and more or less closely attached. 
II. With regard to the Zocecia — 
A. The surface may be 
1. Smooth. 
2. Polished. 
3. Granular. 
4. Verrucose. 
5. Rugose. 
6. Pitted. 
7. Punctulate, minutely porous. 
8. Punctate, with larger perforations. 
9. Reticulate. 
B. The orifice may be 
1. Orbicular. 
2. Elliptical. 
3. Semiorbicular. 
4. Crescentic. 
5. Coarctate. 
6. Trifoliate. 
7. Clithridiate (keyhole-shaped). 
