180 MARINE INVERTEBRATES 



pharynx, when protruded, is very large and long, and appears too 

 large for the worm. The proboscis has four hook-like jaws. 



These worms burrow rapidly and disappear almost 



instantly into the mud or sand. 



GENUS Glycera 



G. americana. Color red or purple ; has branched 

 gills on upper side of parapodia. Found from South Caro- 

 lina to Cape Cod on sandy and muddy shores and flats 

 near low-water mark. 



G. dibranchiata. Has a simple gill on both sides of the 

 parapodia ; about eight inches long and one quarter of an 

 inch wide in the middle ; proboscis one inch long and wider 

 than the body on the upper end. Abundant from New 

 Jersey to Cape Cod. 



ORDER SEDENTABIA 



THE TUBICOLOUS WORMS 



Many of this order construct tubes in which they 

 live permanently. Some species of both Sedentaria 

 and Errantia have habits pertaining to the other. 

 These worms are without a protrusible pharynx and 

 without jaws. The body is usually divided into two 

 or three sections by segments and appendages of dif- 

 ferent forms. They have hair-setee on a limited 

 number of segments only, varying with the species; 

 the remaining segments have uncini, or hooked comb- 

 like rows of setae, which are very small, but often 

 crowded in bunches. Uncini exist also on segments 

 having hair-setae. Parapodia are often lacking on 

 the posterior parts and are usually without cirri. 

 The gills are usually confined to the anterior end and 

 are sometimes represented by tentacles around the 

 head. The different species have characteristic tubes, 

 formed by mucus secreted by epidermal glands. 

 Sometimes the mucus hardens, making a parchment- 

 like tube ; again it cements together grains of sand, 

 or bits of shell, seaweeds, etc. Some species secrete 



