326 EEPOET OF COMMISSIONER OF FISH AND FISHERIES. 



the body is much longer, and the tail is long, slightly tapered, straight,, 

 and obtuse. The Pontonema vacillatum also occurs in similar places in 

 abundance. In this species the male has a short, obtuse, incurved tail j 

 the female a straight, tapering, narrow, obtuse one. Both species are 

 oviparous, and the female genital orifice is near the middle of the body. 

 These worms are from a quarter to half an inch or more in length. 

 Their complete history is not known ; they are closely allied to many of 

 the parasitic worms, and it is possible that in some stages of their de- 

 velopment these are also parasites. 



Of the Eadiates there are also numerous species to be found on these 

 rocky shores. 



Although the purple " sea-urchin," Arbacia punctulata, and the green 

 " sea-urchin," Strongylocentrotus DrobacMensis, (Plate XXXV, fig. 268,) 

 are sometimes met with, their occurrence is irregular and uncertain at 

 low-water in this region. The former occurs in abundance on rocky 

 and shelly bottoms in the sounds ; while the latter occurs chiefly on sim- 

 ilar bottoms in the cold area, and at low-water on the outer rocky 

 shores, and still more abundantly farther north. 



The green star-fish, Asterias arenicola, (Plate XXXV, fig. 269,) is 

 found in large numbers at low- water among the rocks at certain times, 

 but at other times is seldom met with, though a few young specimens 

 can almost always be found by careful search beneath the stones. The 

 adults were very abundant on the shore at Parker's Point, in the latter 

 part of June ; but by the middle of July very few could be found there. 

 Their habit of coming up to the shore may be connected with their 

 reproductive season. They are always abundant on shelly bottoms in 

 the bays and sounds, especially where there are beds of muscles or 

 oysters, upon which they feed. They often prove exceedingly destruc- 

 tive of oysters planted in waters that are not too brackish for their com- 

 fort. They manage to eat oysters that are far too large for them to 

 swallow whole, by grasping the shell with their numerous adhesive feet 7 

 and then, after bending their five flexible rays around the shell so as 

 partly to inclose it, they protrude the lobes and folds of their enormous 

 saccular stomach from the distended mouth, and surrounding the 

 oyster-shell more or less completely with the everted stomach they 

 proceed to digest the contents at leisure, and when the meal is fin- 

 ished they quietly withdraw the stomach and stow it away in its proper 

 place. In this way a large " school" of star-fishes will, in a short timer 

 destroy all the oysters on beds many acres in extent, unless their oper- 

 ation be interfered with by the watchful owners. In one instance, 

 within a few years, at Westport, Connecticut, they thus destroyed about 

 2,000 bushels of oysters, occupying beds about 20 acres in extent, in a 

 few weeks, during the absence of the proprietor. 



In order to stop their operations it is necessary to dredge over the 

 eyster-grounds and destroy all the star-fishes thus brought up, by leav- 

 ing them on shore above high-water mark ; for if simply torn in pieces. 



