CHAPTER Vin. 



SUB-CLASSES LUCERNARIDA AND GRAPTOLITID^. 



The last remaining group of the living Sydrozoa is that 

 of the I/ucernarida (Lat. lucerna, a lamp), under which name 

 are included a considerable number of forms, differing from 

 one another to a great extent in exter- 

 nal appearance. It will be sufficient 

 here to describe one or two tjpical 

 forms. 



One group of the Lucemarida is 

 represented by Zaicernaria itself (Fig. 

 23), which occurs not uncommonly in 

 temperate seas. In Lucernaria we have 

 a cup-shaped body, of a more or less 

 gelatinous consistence, usually found 

 attached by its smaller extremity to 

 sea-weeds, this end of the body being 

 developed into a small sucker. like 

 the Hydra, however, Iiucernaria is not 

 fixed, but can detach itself at will, and 

 can even swim freely by means of the 

 alternate contraction and expansion of 

 the cup-shaped body (or "umbrella," 

 as it is termed). Round the margin of 

 the cup are tufts of short tentacular 

 processes, and in its centre is fixed a 

 single polypite, furnished with a four- 

 ria.22.-TwoBpeciinenBofz». lobed mouth. The essential elements 

 ce™,(wiaaw*irfa attached of reproduction are developed within 



to a piece of sea-weed (after .i / j r 7" • -i. li- j -j. 



Johnston). the body of Ijucernaria itself, and it 



does not give off any generative buds, 

 as so commonly occurs in other forms. 



