24 SERTULAPJA EXIGUA. 



The present species resembles in its general habit Sertularia pumila, 

 and might, without examination, be mistaken for it. It is, however, dis- 

 tinguished from that species by its tumid hydrothecae, and by the wide 

 angle at which their distal portion diverges from the stem ; as well as 

 by the greater length of the internodes and consequent separation of the 

 pairs of hydrothecae. 



No gonangia were present, and the specimen may not have attained 

 its full growth. In some of the hydrothecse the hydranths were fairly 

 preserved, and the opercular bands were recognizable. 



Sertularia tubitheca. 

 PL XVI. Figs. 5, 6. 



Trophosome. — Hydrocaulus attaining a height of upwards of an inch, 

 branched ; branches opposite ; internodes of moderate length, thinning away 

 below every pair of hydrothecae. Hydrothecje long, tubular, cylindrical, 

 free, and divergent for a little more than their distal half, with the orifice 

 circular, abruptly but slightly everted, and having close behind it an 

 annular ridge resembling the margin of a former orifice. 



Gonosome not known. 



Dredged from a depth of 16 fathoms at the Tortugas. 



Sertularia tuhitheca is a small but elegant species. The double-lipped 

 condition of the hydrothecEe was constant in the specimens examined, and 

 seems due to the existence of an earlier orifice, to Avhich the present one 

 has succeeded. It is possible that indications of more than one such earlier 

 orifice would be found in older specimens. 



Sertularia exigua. 



Pi. XVI. Figs. 7, 8. 



Trophosome. — Hydrocaulus minute, simple, attaining the height of about 

 ^ of an inch ; internodes very short, not prolonged by an attenuated con- 

 tinuation below the pairs of hydrothecae. Hydrothecae opposite, not tumid 

 below ; free and divergent on their distal half, and with the opposed sides 

 of each pair parallel to one another. 



Gonosome unknown. 



Dredged off Cape Fear from a depth of 9 fathoms. 



This little Sertularia might be mistaken for S. pumila ; unless, however, 



