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 which 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 

 sphyrodeta are the links which unite these two groups. 

 Should a generic name ever be required for this group, I 

 propose for it that of Thoe, 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 



