OBELIA MARGINATA. 9 
short, alternate hydranth-bearing ramuli which are marked at their origin 
by spiral corrugations, and which, increasing in thickness towards their distal 
ends, gradually pass into the piriform body of the hydranth; perisare very 
opaque. Hydranths large, assuming for the most part a drooping attitude. 
Gonosome. — Gonophores (male?) oviform, supported on short spirally 
corrugated peduncles, scattered on the hydrocaulus. 
Dredged at Tortugas in shallow water. 
The massive-looking hydranths and the enlargement of the hydrocaulus 
towards their base give a peculiar aspect to this little hydroid. The peri- 
sarc, which is very opaque, is apparently continued for some distance over 
the tentacles, as in B. vestita Wright, the only species of the genus hitherto 
described. In the condition of the specimens of B. humilis, however, it was 
not possible to make this out satisfactorily. , 
The massive hydranths and comparatively slight development of the 
hydrocaulus distinguish this species from B. vestita. In both species the 
hydranths exhibit a tendency to assume a drooping attitude. 
It occurred in considerable profusion, creeping over the surface of a sea- 
weed which it covered with a low but rather dense growth. 
. 
Suzorper CALYPTOBLASTEA. 
Trine CAMPANULINA. 
Famiry CAMPANULARID/A. 
Genus OBELIA Peron & LeEsurvr. 
Obelia marginata. 
PL Vin kigs: 1 2. 
Trophosome. — Stem attaining a height of nine inches, monosiphonic, pin- 
nately branched; pinne alternate; stem and pinnx gently zigzag, with a 
strong short process given off from the salient angle of each geniculation, 
and with a joint at the distal side of the process. Hydrothece supported 
on short stout peduncles which rest on the processes of the stem and 
pinne, large, nearly cylindrical, slightly oblique at the inner side of the 
base, and with a circular even orifice which is margined by a narrow, more 
transparent rim. 
Gonosome not known. 
Dredged off Logger-Head Key from a depth of 9 fathoms. 
2 
