122 
SAGARTIAD^. 
The species already described appear to me to be divi- 
sible into four or five groups, which cannot, however, be 
properly considered as higher than sub-genera, the charac- 
ters by whicli they are distinguished being too vague to 
afford a basis for generic rank. 
The most typical group, and that for which, should the 
genus be broken up, I would retain the name Sagartia, 
includes the following species : — miniata, rosea, ornata, 
ichthy stoma, coccinea, venusta, nivea. These have conspi- 
cuous suckers, discharge acontia freely, attain only a mode- 
rate elevation, expand the disk only a little beyond the 
column, are for the most part painted with gay colours, 
often in striking patterns, and in particular have the 
column usually of a rich warm brown hue. 
A group rather less typical than this, I consider to be 
formed by the following species: — sphyrodeta, pallida, 
pur a ; to which will probably be added most of the species 
which I defer to the Appendix. These have no con- 
spicuous suckers ; discharge acontia less and less abun- 
dantly ; are in general destitute of positive colour, and 
have a tendency to a colourless transparency. Nivea and 
spJiyrodeta are the links which unite these two groups. 
Should a generic name ever be required for this group, I 
propose for it that of Tlioe, one of the sea-nymphs. {Hes. 
Th. 245.) 
Troglodytes, viduata, and parasitica may be associated 
as a group departing still more widely from the typical 
form. Their suckers are distinct, but minute ; their power 
of emitting acontia varying (feeble in trog. and vid., strong 
in paras .) ; their tentacles are generally streaked (only 
occasionally in trog.) with lateral longitudinal lines ; their 
column is marked with longitudinal bands of lighter and 
darker colour ; they have the power and habit of greatly 
elongating the column ; and manifest a proneness to become 
