No. 412.] MORTH-AMERICAN INVERTEBRATES. 307 
Corynitis agassizi McCr. 
Trophosome: Colonial, not branched, hydranths with cylindrical, highly 
contractile bodies, and spirally arranged, capitate tentacles. 
Gonosome: Gonophores growing low on body of hydranth or among 
the proximal tentacles. Medusz almost spherical, the surface dotted with 
clusters of nematocysts. Marginal tentacles two or four, nodulated and 
swollen with batteries of nematocysts. 
Habitat: Shells of Mytilis, usually overgrown with incrustations of 
Membranopora. 
3. BOUGAINVILLID. 
Colonial, branching, with distinct perisarc. Hydranths with conical 
hypostome and a single whorl of filiform tentacles. Gonophores borne 
just below the hydranth. Medusz with four radial 
canals, marginal tentacles either single or in clusters, 
and with ocelli at their bases. 
GENERA. sk 
I. BOUGAINVILLIA. Hydrocaulus with dense 
perisarc. Medusz with clustered marginal tentacles 
and with branching oral tentacles. 
2. PERIGONIMUS. Stems with gelatinous peri- 
sarc. Meduse with two marginal tentacles and 
without oral tentacles. 
Bougainvillia superciliaris Ag. 
Trophosome: Colony attaining a height of about 
two inches. Stem irregularly branched, branches 
annulated proximally. Hydranths with inconspicu- 
ous hypostome and from fifteen to twenty tentacles. 
Gonosome: Gonophores borne mostly on pedicels yg. 3, — Bougainvillia 
from ultimate branches. Mature medusz with heavy superciliaris Ag. 
(After Agassiz.) 
manubrium and branched tentacles, those of margin 
arising from conspicuous sensory bulbs. Colony light color with greenish 
tinge, hydranth light rose tint. _Medusz with yellowish manubrium tipped 
with red, sensory bulbs reddish orange. 
Bougainvillia (Margelis) carolinensis McCr. 
Trophosome: Colony sometimes eight to twelve inches high, usually 
much smaller. Stem profusely branching, with hydranths freely dis- 
tributed on both stem and branches, and of elongate and flexible, sub- 
conical form. ‘Tentacles about twelve. 
Gonosome: Gonads borne on both stem and branches, often in clusters. 
