CONGDON. — THE IIYDROIDS OF BERMUDA. 481 



portion of the hydrotheca diverges from the axis to a small degree, 

 distally. There is a proximal diaphragm. 



Edge of hydrotheca provided with a single adcauline and abcauline 

 scallop, each of which is marked by a slight projection at its centre. 

 In older hydrothecae several parallel ridges near the edge and oper- 

 culum may be largely torn away ; in younger consisting of three parts, 

 meeting in ridges extending from the centre to the three projections. 

 A lateral view of the colony presents the edge of many opercula, but 

 shows the upper valve of some. 



Gonosome. Colonies dioecious. Form of gonotheca the same in both 

 sexes (Figures 29-31), more than twice as long as hydrothecae, ovoid, 

 with a flaring mouth. They are most abundant in proximal part of 

 colony, attached to hydrothecae just below diaphragm. A gonotheca 

 was once observed rising from the interior of a hydrotheca. Charac- 

 teristic markings may have been lost as the gonothecae were not well 

 preserved. About sixteen eggs in the single large gonophore (Figure 

 30). Male gonothecae of similar appearance. 



Sertularia brevicyathus Versluys. 



So prolific is this little animal in some places that one can hardly 

 pick up a piece of sponge, seaweed, or large hydroid without finding a 

 dense growth attached. 



Versluys ('99, p. 40) first described it from the Cape Verde Islands, 

 and later Nutting (:04, p. 60) from the Bahamas. Neither author came 

 upon the rather infrequent branches, which are attached at an acute 

 angle just below the hydrothecae and differ in no respect from colonies. 



Stolons are not uncommon. They may be given off like branches or 

 from the tip of the colony. In the latter case they are often as long as 

 a colony. If a number occur in one colony, they are arranged in pairs 

 or are irregularly distributed. 



The gonosome has not been previously described. Gonothecae are 

 usually solitary on a colony, and attached just below a basal hydro- 

 theca. Both male and female gonothecae are sessile, with a constricted 

 opening, a low flaring lip, and wavy surface. They are closely similar 

 to the gonothecae of S. pumila. These have been so completely de- 

 scribed by Weismann as to render further account unnecessary. 



Sertularia versluysi Nutting. 



Sertularia versluysi was first described by Allman from dredgings oflF 



the coast of Bermuda in thirty fathoms. I have only a few colonies, 



which I found on floating Sargassum. 

 vol.. XI, II. — 31 



