CONGDON. 



THE HYDROIDS OF BERMUDA. 



475 



flaring end and one or more deep annulations at the base. Growth in 

 a straight line may result from the addition of successive hydrophores. 

 Their rims are outside the walls of the next in the series and so may 

 be lost off. Pairs of branches arise as hydrophores, attached by short 

 abrupt curves to the 

 opposite sides of a 

 hydrophore, or, less 

 frequently, but one 

 occurs. There is no 

 especial order in the 

 arrangement of hydro- 

 phores. Small colonies 

 result, whose units are 

 partly branching and 

 partly linear. Seldom 

 are there more than 

 four hydrophores in a 

 series ; stolons in a few 

 instances were found 

 terminating branches. 



Large and slightly 

 retractile hydranths 

 terminate each branch. 

 There are sixteen to 

 twenty-five tentacles 

 and the hypostome is 

 short and rounded. 



Gonosome. Ovoid Figdre 23. llalecium marki. Large colony (X CO). 



gonothecae take the place 



of branches (Figures 21, 22). Most colonies examined had from one 

 to three of them. Male and female gonothecae occur on colonies at- 

 tached near to each other on the stolon. The constricted opening and 

 the short deeply annulated pedicel make a straight line down one side. 

 Midway upon it two delicately annulated tubes arise, which are closely 

 confluent with each other and with the gonotheca. At the curiously 

 annulated mouth of the latter they end as hydrophores which bear 

 hydranths. 



The blastostyle in either sex is joined with the coenosarcal column, 

 which branches into the two tubes. The single female gonophore 

 contains two large eggs, one above the other. The male gonophore is 

 also single and ovoid. 



llalecium heanii is the only species of the genus which has a gono- 



