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The Ohio Journal of Science [Vol. XXI, No. 4, 



Terwilliger's Pond, South Bass Island. Towards the last 

 of July almost every Pectinatella is producing both statoblasts 

 and these colonies in large numbers. The non-sexual stato- 

 blasts seem to be produced in numbers later in the season 

 than the sexual colonies. I could not decide whether there 

 is a natural aperture for emergence or whether they go through 

 breaks in the envelope, but the latter seem the most likely. 

 (Fig. 1). 



Fig. 1 



Fig. 2 



Figure 1. Pectinatella, adult. One cluster of branches showing larval colonies 

 and two statoblasts. X 25. 



Figure 2. Diagrammatic sketch of free swimming colony. X 100. 



As the larval colony is freed from the parent it is a ciliated 

 float or bladder with a number of polyps below. There may 

 be from one to five polyps, the usual number being four. As 

 the colonies swim upwards by ciliary action, then sink, sw4m, 

 sink, they have much the appearance of microscopic balloons. 



They are from two to five millimeters long and about half 

 as wide as they move in the water. The range of variation in 

 length is great because the polyps of the cyst may be retracted 

 into the gelatinous mass at the base of the float or may be 

 extended downward with outspread tentacles swinging for 

 food. The cyst also may contract. 



