No. 413.] WORTH-AMERICAN INVERTEBRATES. 387 
t, £. dumosa Flem. (Fic, 23). 
Trophosome: Stem creeping, sometimes erect and fascicled ; hydrothece 
tubular, margins devoid of teeth or operculum, usually sessile. 
Gonosome: (?) 
D2 DG HCAT IE AN. NORE IG. 24), 
Trophosome: Stems creeping, simple; hydrothecz tubular, sessile. 
Gonosome: Gonangia large, elongate, obovate or oblong, somewhat 
resembling those of certain campanula- 
rians. Medusz large, transparent, with 
Fic. 23. 
Fic. 23.— Lafea dumosa Flem. (After Hincks.) 
Fic. 24.— Lafea calcarata A. Ag. (Adapted from A. Agassiz.) 
gonads suspended in folds beneath the radial canals; marginal tentacles 
numerous in mature specimens, only two when first set free. 
Habitat: Usually parasitic upon sertularian hydroids. 
3, L. pygmea Alder. 
Trophosome: Stem creeping; hydrothecz minute, tubular, elongate, 
borne on very short annulated pedicels. 
Gonosome : (?) 
Habitat: Parasitic on various hydroids. 
HALECID&. 
Of this family a single genus comes within the range of this synopsis : 
namely, the type genus, Halecium (Oken), the characters of which may be 
summarized as follows: 
Trophosome: Colony more or less branched, attached by a creeping 
hydrorhiza. Hydrothece often shallow and disk-like, or funnel-shaped 
(hydrophores). In many species with double or triple margins due to 
