HYDROIDS OF THE WOODS HOLE REGION". 
385 
Ovaries, the generative organs of the medusae. The term is often applied to both sexes. They are 
situated either on the proboscis, along (under) the radial canals, or in both places. 
Pedicel, the stem or stalk that supports the hydranth and hydrotheca. 
Perisarc, an external chitinous skeleton which invests and gives support to the stems, branches, etc., of 
most hydroids. 
Planula, a free-swimming, usually pear-shaped ciliated body into which the ovum immediately 
develops in the course of the hydroid life cycle. 
Proboscis, the portion of the hydranth body that usually surmounts the basal tentacles and contains 
the mouth, or the pendant mass which hangs like the clapper of a bell from the center of the bell 
cavity of a medusa. It is often called the manubrium. 
Radial canals, tubes which are found on the under side of the umbrella of a medusa and lead from the 
digestive cavity to the circular canal around the bell margin. 
Sarcostyle, the highly extensible defensive “person” found in the Plumularidse. It contains nemato- 
cysts or adhesive cells or both, and is made up of ectoderm, mesogloea, and endoderm. In some 
cases a body cavity has been demonstrated, but neither mouth nor tentacles. 
Sense-bulb, a swelling, usually at the base of a marginal tentacle of a medusa, which is supposed to be 
sensory in function and often contains conspicuous pigment spots known as “eye-specks” or “eye- 
spots,” supposed to have to do with the function of sight. 
Septum, a horizontal partition which partly divides the cavity of the hydrotheca from that of the 
pedicel. 
Spiral zooid, a peculiar defensive “person,” found in JPi /dr actinia, which is long and without a mouth, 
but capable of bending itself in a twist or spiral. 
Sporosac, a sac-like gonophore without evident medusoid structure. 
Tentacles, the slender, motile organs which are arranged usually in a radiate manner around the pro- 
boscis of the hydranth. Theyare “filiform” when without rounded distal knobs, and “capitate” 
when they are knobbed at the ends. In the medusa the “marginal tentacles ” surround the bell 
margin and the “mouth tentacles” surround the mouth. 
Trophosome, the entire assemblage of structures in the colony, except those directly associated with the 
reproductive parts. It includes the hydrocaul us, liydrorhiza, hydranths, etc. 
Velum, a delicate membrane which is stretched across the bell opening of a hydroid medusa. It is 
attached to the bell margin and has a large circular opening in its center. 
SYSTEMATIC INDEX . 1 
Page. 
iEquorea albida 3S2 
Antennularia 367 
amerieana 368 
aiitpanina 367 
rugosa 368 
Bougainvillia 329 
carolinensis 330, 376 
superciliaris 330, 376 
Bougainvillidae 329 
Calycella 355 
syringa 355 
Calypteroblastca 341 
Campanulinidse 353 
Campanularia 344 
amjjhora 347 
angulata .7. 347 
calceolifera 348 
edwardsi 346 
flexuosa 348 
hincksii 345 
Page. 
Campaimlaria minuta 345 
negleeta 346 
potermm 344 
verticillata 347 
volubilis 345 
Campanularidse 341 
CJadoearpus 368 
flexilis 368 
Clava 327 
leptostyla 327 
Clavidaj 327 
Clytia 343 
bicophora 343,379 
cylindrica 343 
grayl 314 
noliformls 343, 379 
Cordylophora 327 
lacustris 327 
Corymorpha 337 
pendula 337, 370 
iNo synonyms are included in this index. 
F. C. B. 1899—25 
