CONGDON. 



THE HYDKOLDS OF BEllMUUA. 



479 



process which joins another tube of similar structure. The large tube 

 and all hydrothecae-bearing tubes are segmented, as well as the others, 

 just before uniting with them. 



The present species is an illustration of the difficulty which is found 

 in delimiting the genus Sertularia and some other genera of the same 

 family. The genus is confined by Nutting (: 04, p. 37) to those species 

 in which the operculum is well defined or stretched tightly over the 

 top of the hydrotheca. Though neither condition occurs here, the 

 characters of hypostome and gonosome place the species unmistakably 

 in this genus. Thidaria pinnata, described by Allman from the Double- 

 headed Shot Key, is similar in trophosome, but the hydrothecae are 

 less confluent (Allman, '77, p. 28). The gonosome is not known. Ser. 

 tularellx didans is also much like this species (Nutting, : 04, p. 88). 

 The stem is, however, unfascicled and the hydrothecae provided with 

 a constant border. 



Figures 29-31. Sertularella kvmilia. 



Figure 20. Female gonotlieca, one egg remaining (X 25). 

 Figure 80. Female gonotlieca, eggs not discharged (X 25). 

 Figure 31. Male gonotlieca (X 25). 



Genus SERTULARIA Linnaeus (in part), 1767. 



Sertularia humilis (new species). Figures 29-32. 



This is one of the hydroids most common at Bermuda. It grows so 

 abundantly between tide marks as to make thick brown mats, which 



