122 



LIFE BY THE SEASHORE. 



made up of very numerous whitish cells or chambers, each 

 of which once contained a worm. Living Polyzoa are quite 

 common on the shore rocks. Among those to be found 

 there in the active condition may be mentioned Flustrella, 

 which forms a soft brownish encrustation on the stalks of 

 Fucus, and has its surface covered by numerous spines; 

 Membranipora, which spreads like delicate lacework over 

 the broad fronds of Laminaria; and many others. None of 

 them can be properly studied without the aid of a micro- 

 scope, and are only mentioned here because they are sure to 

 be encountered, and may puzzle the student. 



KEY FOR IDENTIFICATION OF COMMON BRISTLE-WORMS. 

 A. Anterior region with well- B. Anterior region with few 



developed tactile organs. Para 

 podia well-developed locomotor 

 organs, usually with dorsal and 

 ventral cirri. 



A. 



ex :} 



Dorsal cirri 

 panded 



Dorsal cirri form 

 filamentous sen- 

 sory organs 



tactile organs, often Avith nu- 

 merous respiratory organs. 

 Parapodia reduced, cirri absent, 

 or dorsal cirri represented by 

 gills. 



f Aphroditidae \See previous 

 \Phyllodocidse / chapter. 



Nereidse 



Nereis. 



Prostomium short. 



Dorsal cirri absent 

 or indistinct . > 



podia 



Prostomium iuiig,-v 



Gill when pre- VGlyceridee 

 sent dorsal J 



B. 



Glycera. 



Head without ap-^ 

 pendages. Pros- 1 

 tomium fused to | 

 peristomium . j 



Prostomium with-\ 

 out appendages, 

 peristomium 

 with two tenta- V 

 cular cirri. Gills 

 curved over I 

 back . J 



Arenicolidse . Arenicola. 



. Spionidae . Nerine. 



