THE GENERA OF HOLOTHURIDEA. ai 
Genus Liosoma.—Tentacles 12, scutiform. Body cylindrical, 
short. 
Genus Caudina.—Tentacles 12, digitately divided at the end. 
Body strongly contracted behind. Skin very rough, with numer- 
ous calcareous plates. 
Genus Echinosoma.—Tentacles 12, stump-like. Body ascidian- 
like. Skin covered with large calcareous scales, which may carry 
a centre spine. 
Genus Ambolus—Tentacles 15, stump-like. Csophageal 
calcareous ring wanting. 
Family I1.—Dendrochirote. 
Feet- and lung-bearing Holothurians, with a completely de- 
veloped _ambulacral system, and tree-like branching tentacles. 
Five muscles which spring from the circum-cesophageal plates, 
go through the whole cavity of the body. 
Sub-family [.—Stichopoda. 
The small feet of the ambulacra arranged in well-marked 
rows ; the interambulacral areas almost always without any feet. 
Genus Cucumaria—tIn all the five ambulacra similarly 
formed feet stand in several rows; some species have them on 
the interambulacral areas. Body generally sub-pentagonal. 
Tentacles 10, frequently with two smaller ones, which conform 
to the middle radius of the trivium. 
Genus Oczus.—The ambulacra, at least upon the back, with 
only a single row of widely-separated feet. Tentacles 10, 
irregularly branched, the two middle central ones smaller than 
the others. Large calcareous plates in the skin. 
Genus Colochirus——The feet of the ventral surface in three 
clearly separated rows ; upon the back only ambulacral papille. 
The two middle tentacles of the ventral side smaller than the 
remaining eight. Anus with or without calcareous teeth. 
Genus Echinocucumis.—Feet in five rows. Ten dissimilar, 
branching tentacles. Skin covered with long spiny calcareous 
scales, 
Sub-family Gastropoda. 
Feet arranged in well-marked rows upon the clearly-defined 
ventral area. No feet on the back. Calcareous plates in the 
form of large scales. 
Genus Psolus.—Characters of the sub-family. 
Sub-family Sporadipoda. 
Feet surrounding the whole body evenly, rarely or never 
_ showing an arrangement into rows. 
Genus 7Zyone—Tentacles 10, of which two on the ventral 
side are smaller. Feet more or less densely scattered over the 
whole body, but occasionally an indication of rows can be seen. 
Anus with or without calcareous teeth. 
Genus 7/yontdium—Tentacles 20. Five large pairs alter- 
nating with five small ones. The small feet are sometimes quite 
