Handbook of Paleontology 177 



Marsh Fiddler discussed above is the most abundant. 

 Mud Crabs have been found in salt marshes, and Beach 

 Fleas under drift and vegetable debris. Another small 

 snail (Littorinella minuta), characteristic of the mud 

 flats, is found in pools and ditches of salt marshes in 

 numbers. Small fishes and various aquatic birds feed 

 largely upon it. The Ribbed Mussel lives over salt 

 marshes along- borders of ditches and streams wherever 

 there is sufficient moisture, with the shell partially im- 

 bedded in the mud or among the roots of the grass and 

 anchored by a stout byssus. 



There are various other associations. Coral reefs have 

 their own life. The madrepore or stone corals are the 

 reef-builders and with them are associated the hydro- 

 corallines such as the Elk Horn Coral. Here occur also 

 the Sea Fans, Sea Whips and Sea Feathers. Character- 

 istic mollusks, worms, crabs, starfishes, sea urchins etc. 

 are to be found here. It has been aptly stated that coral 

 reefs are as thickly inhabited by other forms of life as 

 the forests by birds and insects. 



Parasites and commensals constitute another type of 

 association. Two forms are rather interesting and may 

 be met with. One of the sea anemones, the Parasitic 

 Anemone (Edwardsia leidyi) lives in one of the jelly- 

 fishes, the Rainbow Jelly. It is a long, dull-pink, thread- 

 like form looking like a worm. The female of the Oyster 

 Crab (Pinnotheres ostreum) lives when mature in the gill 

 cavity of the oyster. It is highly esteemed as a delicacy 

 and sold at a high price. The female shell is pinkish 

 white in color and thin, while the male is brown with 

 light-colored central stripes and four white spots and has 

 a hard shell. The male swims freely and has strong 

 claws and legs, but the legs of the female are so weak 



