156 



MARINE INVERTEBRATES 



ORDER CYDIPFIDA 



GENUS Pleurobrachia 



P. rhadodactyla. 



A transparent spher- 

 ical body, one inch to 

 one and a half inches 

 in diameter, with 

 eight combs or plates 

 of flat cilia extending 

 from pole to pole. 

 At one pole is the 

 mouth, like a slit, at 

 the other a small area 

 in the center of which 

 is an eye-spot. From 

 the body hang two 

 tentacles, half a yard 

 or more in length, 

 fringed with cilia. 

 The tentacles are 

 very contractile and 

 can be rolled up or 

 expanded with great 

 rapidity; they take 

 graceful curves as the 



animal moves rapidly through the water. Pleurobrachia has a pink tint, 



and prismatic colors play over it from the vibrating cilia. It is a beautiful 



and interesting creature to watch. Found 



along the shores of Massachusetts and Maine. 



ORDER LOBATA 

 GENUS Bolina 



B. alata. Slightly oval in form ; lower 

 part of the body divided into two large lobes 

 which hang below the mouth. Four of the 

 swimming-plates are shorter than the other 

 four and terminate in curious processes or 

 short appendages called auricles. Bolina is 



, i: i ,1 i liolina nlnta. soen from the broad 



about two inches m length, and is very side . 0> eye . speck . m , mouth . r< au . 

 delicate, transparent, and phosphorescent, ricies ; v, digestive cavity ; g, A, short 

 Its contractile power enables it to vary in ^ows of flappers^ <i,y,jong rows of 

 outline to a considerable extent. It has a 

 slow undulating motion, and sometimes 

 carries its lobes uppermost and open. Usu- 

 ally found associated with Pleurobrachia from Massachusetts northward. 



B. septentrionalis. Found on the northern Pacific coast. 



B. vitrea. A species found in Florida. 



PleurobracJiia rhododactyla, in motion. 



ng in 



the larger lobes; i, base of gullet. 

 About half natural size. 



