HY DROIDS OF THE WOODS HOLE REGION. 
359 
SERTULARIDjE. 
Trophosorne . — Hydrothecse sessile, more or less agnate to the stem, and arranged oil both sides of 
the stem and branches. Hydranths with conical proboscis and a single whorl of filiform tentacles. 
Gonosome .. — Gonangia producing planulse. No medusae. 
Key to the genera of Sertularidee found in the Woods Hole region. 1 
A. HydrothecEe in strictly opposite pairs, a pair to eacli internode of the stem or branch. 
a. Operculum, "when present, in two pieces 
a'. Operculum, when present, in one piece only 
A'. Hydrothecse subopposite, usually deeply immersed, more than two to each joint of stem or branch 
A". Hydrothecse strictly alternate. 
a. Hydrothecse placed on opposite sides of stem and branches 
a’. Hydrothecse placed on the front of branches and curved alternately to the right and left 
SERTULARIA. 
Tropliosome .. — Colony usually branched; stems and branches divided into regular internodes, each 
of which bears a pair of strictly opposite hydrothecse. Hydrothecse either without an operculum or 
with a very delicate one composed of two pieces. 
Gonosome . — Gonangia without an internal marsupium. 
Key to sp>ecies of Sertularia found in the Woods Hole region. 
A. The two hydrothecse composing a pair scarcely touching each other in front S. pumila. 
A'. The two hydrothecse in contact for at least half their length. 
a. The width of a pair of hydrothecse at their bases considerably less than distance from bottom of 
hydrothecse to the node below S. comicina. 
a'. The width of a pair of hydrothecse at their bases not much less than distance from bottom of hydro- 
thecse to the node below .S', complexa. 
Sertularia pumila Linn. Fig. 55. 
(Syst. Nat., p. 1306.) 
Trophosorne . — Colony small, branched 
or unbranched ; stem divided into regu- 
lar internodes, each bearing a pair of 
hydrothecse. Hydrothecse stout, regu- 
larly curved, the approximated sides of a 
pair not in contact; aperture bilabiate, 
often showing a very delicate operculum 
composed of two valves. 
Gonosome . — Gonangia ovate, with a 
short pedicel and a terminal collar con- 
taining the aperture. 
Distribution . — Rather common in the 
Woods Hole region in shallow water. 
Often found growing over seaweed. 
Sertularia cornicina ( McCr. ) . Fig. 56. 
(Dynamena comicina McGr., Gymnophthalmata of Charleston Harbor, p. 102.) 
Trophosorne . — Colony usually of a single upright stem not over half an inch high. Hydrothecse 
more slender than in 8. pumila. and the pairs are in contact for a considerable part of their contiguous 
sides. Colony almost invariably overgrown by a campanularian ( Hebella calearata) which the original 
describe!- took to be a part of the sertularian, the campanularian disposing its curved tubular hydro- 
thecse symmetrically in pairs above the pairs of hydrothecse of the sertularian. 
Gonosome. — U nknown. 
Distribution . — Vineyard Sound, 8 fathoms, on Halecium gracile and on Zostera ( Veri-ill). My 
specimens were sent by Mr. Walmsleyto Professor Osborn, of Hamline University, labeled “8. pumila.” 
Sertularia. 
Diphcisia. 
Thuiana. 
. . . Sertularella. 
Hydrallmania. 
1 A satisfactory classification of this group is still to be devised. The one adopted here will do fairly well for the 
genera and species in the territory under consideration, but would be unsatisfactory if applied to the Sertularidse in general. 
