24 SERTULARIA 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 hydrothecx, 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 hydrothece. 
No gonangia were present, and the specimen may not have attained 
its full growth. In some of the hydrothece the hydranths were fairly 
preserved, and the opercular bands were recognizable. 
Sertularia tubitheca. 
PLXVE 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 hydrothece. Hydrothece 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 tubitheca is a small but elegant species. The double-lipped 
condition of the hydrothec was constant in the specimens examined, and 
seems due to the existence of an earlier orifice, to which 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. 
Pl. 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 hydrothece. Hydrothece 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, 
