HYDROIDS OF THE WOODS HOLE REGION. 
365 
PLUMULARID/E. 
Tropliosome. — Hydrothecae sessile, usually adnate by one side, arranged on the upper sides of 
the hydrocladia or hydrotheca-bearing branchlets. Nematophores 1 always present. 
Gonosome. — Gonangia often inclosed in protective contrivances, such as modified branches or pod- 
sliaped receptacles called “ corbuhe.” No medusae. 
Key to genera of Plumularid.se found in the Woods Hole region. 
A. Nematophores trumpet-shaped, not immovably fixed to the hydrothecae. 
a. Branching dichotomous, the hydrocladia springing from the upper side of the branches Monostxchas. 
a'. Branching strictly pinnate, the hydrocladia, or some of them, forked Schizotricha. 
a". Branching verticillate or scattered. Ccenosarc canaliculated in main stem Antennularia. 
A'. Nematophores not trumpet-shaped, immovably fixed to hydrotheeae or other parts of colony. Gonangia 
protected by special, usually forked, branches bearing nematophores without hydrotheeae Cladocarpus. 
MONOSTXCHAS. 
Tropliosome. — Colony dichotomously branched. Hydrocladia borne on upper sides of branches. 
Gonosome. — Gonangia ovoid, borne at bases of hydrotheeae. 
Monostaechas quadridens (McCr. ). Fig. 69. 
( Plumularia quadridens McCrady, Proc. Elliott Soc., vol. I, No. 1, p. 199.) 
Tropliosome. — Colony erect, composed of a main stem with branches which 
themselves branch dichotomously, bearing hydrocladia at their points of junction 
and also on their upper sides; hydrocladia composed of internodes, every alternate 
one of which bears an hydrotheca. Hydrotheeae cup-shaped, with even margins, 
adnate for about half their length. Nematophores trumpet-shaped, three asso- 
ciated with each hydrotheca, and usually two on each internode of hydrocladium 
that does not bear hydrotheeae; a row of nematophores is also found on the upper 
side of each branch from which hydrocladia spring. 
Gonosome. — Gonangia ovoid or pyriform, borne on short pedicels just below 69. Monosttechasquad- 
the hydrothecie. ridens (McCr.). 
Distribution . — Dredged by the Albatross near Marthas Vineyard. Depth, 22 fathoms. The 
species is common southward to the West Indies in moderate depths. 
SCHIZC XTRICHA. 
Tropliosome. — Colony consisting usually of a cluster of simple, upright stems, giving forth 
hydrocladia in a pinnate manner. Hydrocladia in mature specimens forked. 
Gonosome . — Gonangia ovoid, tubular or cornucopia-shaped, borne on the main stem, branches, 
or hydrocladia. 
Key to species of Schizotricha found in the Woods Hole region. 
An hydrotheca in the axil of each hydrocladium 
No hydrotheeae in the axils of the hydrocladia... 
Schizotricha tenella (Verrill). Fig. 70. 
(Plumularia tenella Verrill. Invertebrated Animals of Vineyard Sound, p. 731.) 
Tropliosome . — Colony in the form of very delicate white plumes, 1 to 3 inches high, each plume 
consisting of a central stem giving off alternate hydrocladia with hydrotheca at base of each; 
hydrocladia often forked in mature specimens, with internodes and hydrotheeae much as in the last 
species, but with an additional short internode often intercalated. Nematophores as in the last species, 
except that there is but one to each intermediate internode. 
1 The nematophores are minute trumpet-shaped or tubular organs composed of ehitin and usually associated with 
the hydrothecEe, two, one on each side, being found near where the margin of the hydrotheca joins the stem to which it 
is adnate, and one just in front of the bottom of the liydrotheca. Others are found on the branches, stem, and protective 
contrivances which inclose the gonangia. The nematophores contain highly remarkable structures known as sarcostyles 
that are capable of enormous extension. They are morphologically "persons” of the colony. 
S. tenella. 
S. gracillima. 
