308 THE AMERICAN NATURALIST. [VOL. XXXV. 
Meduse much as in previous species, but with narrower and shorter hypo- 
stome. Colony light grayish tinged with dull green, hydranths with red- 
dish tint. _Medusz with brick-red manubrium and sensory bulbs, ocelli 
black. 
Habitat: Piles of docks, occasionally on seaweed and floating timbers. 
Perigonimus. 
Colonial, rarely attaining a height of more than ¥% of an inch, simple or 
branched, perisarc usually gelatinous and extending to base of tentacles. 
Hydranths relatively large and with conical hypostome. Medusz borne on 
hydranths or on stem or branches, bell-shaped and with two to four 
tentacles with bulbous bases. 
Perigonimus jonesit. 
(American Naturalist, vol. xxviii, p. 27.) 
Trophosome: Colonial, branching freely, with thick, gelatinous perisarc, 
often wrinkled, extending to, or even including, the bases of tentacles. 
Hydranths with subconical hypostome, 
with about sixteen filiform tentacles, 
alternately elevated and depressed. 
Gonosome: Meduse ovoid or hemi- 
spherical, with four radial canals and 
ocelli, but having only two tentacles, 
which are often spirally coiled and dis- 
posed within the subumbrellar cavity. 
Habitat: Found only upon the 
abdomen and legs of the spider crab, 
Labinia marginata, Cold Spring 
laGborp ole 
4. EUDENDRID&. 
Colonial, often branching with great 
profusion, becoming quite arborescent. 
Perisarc distinct, more or less annulated, attached by creeping hydro- 
rhiza. Hydranths flask-shaped, with sharply differentiated, trumpet-shaped 
hypostome. Tentacles filiform, forming a single whorl about the base 
of the hydranth. Male gonophores borne in a verticil just beneath the 
tentacles of hydranth, which in some species become directly metamor- 
phosed into gonophores. Female gonophores not verticillate, usually borne 
on body of hydranth, which often becomes transformed into gonophores 
with their peculiar spadiceous, finger-like coils enclosing the ova. The_ 
family includes a single genus, Eudendrium, fairly characterized in the 
accompanying cut. The following species are designated: 
Fic. 4.— Perigonimus jonesii. 
