98 LIFE BY THE SEASHORE. 



sand, and may be obtained either by digging in the sand, 

 or, quite as frequently, under stones which are resting on a 

 bed of muddy sand. It does not throw off the elytra quite 

 as readily as the common Polynoe, but has almost a worse 

 fault in the tendency to break into pieces on very slight 

 provocation. It has, on the other hand, the great advantage 

 of preserving well, and making a beautiful preparation when 

 once it can be obtained intact. 



Some interesting points of structure may be noticed. 

 The scales begin on the second segment, and up to the 

 twenty-sixth segment occur on alternate segments; after 

 this they are borne on every segment. In addition each 

 segment bears two small gills which are covered by the 

 scales. These gills are believed not to be homologous with 

 dorsal cirri, which are here represented only by the scales. 

 The last segment of the body bears two extremely fragile 

 cirri. The worm is sometimes called "brown cat" by 

 fishermen, who call another sand worm (Nephthys) " white 

 cat." There is some superficial resemblance between the 

 two, but the "white cat" has no scales, and is much more 

 rapid in its movements. 



The next family we shall consider is that of the "leaf- 

 worms" (Phyllodocida?.). The family includes some of the 

 most beautiful of worms, remarkable alike for beauty of 

 form, of movement, and of colour. They owe their name 

 and much of their beauty to the fact that their cirri are 

 converted into leaf-like plates which are used in swimming. 

 These leafy plates are often brightly coloured, green tints 

 predominating in their colouring, and they stand out like 

 oars at the sides of the body. When the animals move a 

 wave of motion sweeps down the long rows of oars, while 

 at the same time the long lithe body sways from side to 

 side. If we add that some forms possess a lovely changing 

 p>ieen, in addition to the bright colour seen in repose, it is 

 easy to understand that the Phyllodocids are often beautiful 

 indeed. 



It is interesting to note some of the differences between 

 their leafy plates and the scales of Polynoids. In the latter 

 the scales are attached by a small area usually near the 

 centre, so that the whole series forms an armature of 

 overlapping scales, the elements of which are capable of 



