COELENTERATA 51 



to New Jersey (Great Egg* Harbor Bay); rare in 

 New Jersey and not reported in recent years . 



Sertularian Hydroids 



Hydroids with hydrotheca sessile, that is, 

 without stalks, and arranged on both sides of the 

 branches. 



Sertularia pumila Linne 



PLATE II. Fig. 10 



Usually branched; stem divided into regular 

 nodes and internodes, each bearing a pair of oppo- 

 site hydrothecae which hardly touch each other in 

 front; no stalks. 



Reproductive polyps (gonosomes) ovate with a 

 short stalk and a terminal collar containing an apert- 

 ure. No free swimming medusae are liberated. 



Grows in shallow water on sea weed, eel grass, 

 etc., from Arctic Seas to New Jersey. Common near 

 Woods Hole, Massachusetts; occasionally found on 

 the New Jersey coast on Fucus (Rock Weed) or eel 

 grass. Frequently grows flat on the seaweed with a 

 few upright branches about an inch or so high. 



Thuiaria argentea Ellis and Solan der 



PLATE II. Fig. 1 



Dark stem with silver branches ; often a foot or 

 more in length; stem and branches divided into 



