306 THE AMERICAN NATURALIST. [VOL. XXXV. 
Rhizogeton fusiformis Ag. 
(Contr. Nat. Hist. U. S., vol. iv.) 
Trophosome: Colony much as in Clava. Hydranths of about inch in 
height, tentacles about twelve in number, borne on distal half of polyp. 
Gonosome: Gonophores oval, arising from hydrorhiza on short pedun- 
cles, the whole invested by filmy perisarc. 
Habitat: Rocky pools between tide marks, Massachusetts Bay. 
Cordylophora lacustris Allman. 
Trophosome: Colonial, profusely branching, hydranths with scattered 
filiform tentacles. 
Gonosome: Gonophores borne on branches, ovate and with definite 
investment of perisarc. 
Habitat: Brackish, and fresh 
waters in lagoons, ponds, etc. 
2. CORYNID. 
Colonial, hydranths with capitate 
tentacles only, scattered over the 
elongated bodies, or growing in 
indefinite whorls. Gonophores usu- 
ally borne among the proximal ten- 
tacles, or from body of polyp and 
producing medusz, which may be- 
come free or remain attached. 
GENERA. 
I. SYNCORYNE. Stem invested 
by definite perisarc; hydranths clavi- 
form. 
2. CoryNiTiIs. Stem devoid of 
definite perisarc ; hydranths sessile, 
with long, cylindrical bodies. 
Fic. 2.— Syncoryne mirabilis Ag. Syncoryne mirabilis Ag. 
(After Agassiz.) : 
Trophosome: Branched, perisarc 
smooth or with only slight indication of annulations. Hydranths with 
numerous capitate tentacles. 
Gonosome: Medusz borne on hydranth body. These are of two forms, 
one free and developing earlier, hemispherical, with well-developed ten- 
tacles, with an ocellus at their base; the other fixed, tentacles rudimentary, 
and devoid of ocelli. 
