MONOGRAPH OF THE EXISTING CBINOIDS. 59 



GLOSSARY OF TERMS USED IN THE DESCRIPTION OF A COMATULID. 



A. 



Aboral. — The surface opposite to that which includes the mouth and the anal tube; 



the dorsal surface. In life this is the lower surface under normal conditions 



(see figs. 77, p. 130, 78, p. 131, 79, p. 132, 80, p. 133, 81, p. 134, 82, p. 135, 101, 



p. 163, 107, p. 173, 114, p. 181, 160-162, p. 223, and 163, p. 225). 

 Adamhulacral. — Bordering the ambulacral grooves. 

 Adapical. — Aboral or dorsal. 

 Adolescent autotomy. — See under Autotomy 2. 

 Adoral. — The surface upon which is situated the mouth and the anal tube; the 



ventral surface. In fife this surface is uppermost under normal conditions 



(see fig. 117, p. 183, and p. 110 [7]). 

 Ambulacra. — (1) Shallow grooves running along the ventral (adoral) surface of the 



pinnules and arms and travereing the disk, converging at the mouth; they 



serve to convey food to the mouth (see figs. 15-19, p. 67, 22-27, p. 69, 45a, p. 79, 



and 117, p. 183). 



(2) This term as used by Guilding is equivalent to cirri. 

 Ambulacral grooves. — See Ambulacra (1). 

 Ambulacral lappets. — Small epidermal folds which border the ambulacral grooves 



on either side, giving their margins a scalloped appearance. 

 Ambulacral plates. — Small plates developed in two rows (more rarely m a single row) 



along either side of the ambulacral grooves; the Side and Covering plates taken 



together (see figs. 7, p. 63, 18, 19, p. 67, and 55, p. 81). 

 Ambulacral structures. — (1) AU the structures, both calcareous and noncalcareous, 



internal and external, associated with the ambulacra. 



(2) The structures in the radial, as opposed to the interradiaJ, portion of 



the animal. 

 Anal appendage. — See Atial process. 

 Anal area. — The interambulacral area at or near the center of which is situated 



the anal tube (see figs. 15-19, p. 67, and pp. 110 [7], 111). 

 Anal funnel. — See Anal tube. 

 Anal interradial. — The interradial situated on the margin of the ana^ area. 



In cases where there is only one interradial present it is invariably the 



anal interradial, and this is then known simply as Anal x. 



In recent species if the anal interradial is present, all the other interradials 



are also present (see figs. 115, 117, p. 183, and pp. 335-339). 

 Anal plate. — See(l) Radianal and (2) Anal x. 

 Anal process. — ^The name given to a short segmented process borne on the posterior 



interradial (anal x) in the so-caUcd Thaumatocrinus renovatus. Thaumato- 



crinus renovatus is the young of tlie species later described as PromacTwcrinus 



abyssorum, and the anal process is the rudiment of the first of the interradial 



arms to be formed. Similar processes, each developing into an interradial arm, 



subsequently appear on all the other interradial plates (see figs. 115-117, p. 183, 



and pp. 335-339). 



