592 THE AMERICAN NATURALIST. [Vor. XXXV. 
R. floridanus Ag. 
Very similar to the preceding, though smaller, and of southern range. 
“#iquorea albida A. Ag. 
Bell subhemispherical, tending to conical above; radial canals very 
numerous, and with two or three marginal tentacles borne between each; 
otocysts also numerous, spherical, and containing several small otoliths ; 
above the base of each of the larger tentacles is a tentacular spur, similar to 
those of Rhegmatodes; manubrium short and with simple oral lobes. In 
size mature specimens vary from one to two inches in diameter. Not 
uncommon in the vicinity of Buzzards Bay during later summer. Hydroid (?). 
Zygodactyla grenlandica Ag. 
This is one of the largest of the Hydromedusz, sometimes measuring 
twelve to fifteen inches in diameter; bell rather low and flat; radial canals 
very numerous; marginal tentacles long and very contractile, and several 
between the terminals of the radial canals; above the bases of the tentacles 
are conical spurs quite similar to those of the two preceding genera; manu 
brium large and elongated, extending beyond the velum when fully ex- 
panded, and with densely frilled or fimbriated oral lobes; gonads borne 
along the lines of the canals as in the former genera. Habitat from Green- 
land, Maine, Massachusetts, southward. Hydroid (?). 
TRACHOMEDUS&. 
The synoptic characters of this order have already been given. Of 
representatives there are comparatively few which come within the range of 
the present synopsis. No details of arrangement 
under appropriate families will therefore be 
undertaken in this connection, but the genera 
and species will be noted so far as known, 2 
some placed provisionally under the order, 
whose exact affinities there is doubt. Hydro 
generation suppressed. 
of 
Trachynema digitale A. Ag. (FIG. 59). 
Medusa elongate bell-shaped, the apex rather 
sharply conical; radial canals eight, rather wide; 
tentacles numerous and somewhat fragile; om 
cysts four, rather large, and with colored otoliths ; gonads eight, finger-like 
and suspended from the upper portions of the radial canals. Size of 
Fic. ma digitale 
A. Ag. (After A. Agassiz.) 
