Limitation of Genera among the Hydroida. 357 
rocodonic, never become free, and the marginal tentacles then 
remain in an imperfectly developed state. 
Syncoryne Sarsii, Lovén, = Syncoryne decipiens, Dujardin. 
Syncoryne ramosa, Lovén. 
Syncoryne (sp.), Désor. 
Syncoryne turricula, M‘Crady (sp.), = Sarsia turricula, M‘Crady. 
M‘Crady figures and describes the Medusa of this species; but 
his description of the trophosome is not full enough for a satisfactory” 
diagnosis. 
Syncoryne mirabilis, Agass. (sp.), = Coryne mirabilis, Agass. 
Syncoryne exunia, Allm. (sp.), = Coryne eximia, Allm. in Ann. 
Nat. Hist. 1859. 
Syncoryne gravata, Wright (sp.), = Coryne gravata, Wright. 
Provisional and Doubtful Species. 
Syncoryne bryoides, Khr.,= Tubularia muscoides, Linn. 
Syncoryne Lister, Van Ben. 
3. ZANcLEA, Gegenbaur. 
Trophosome.—Ccenosare consisting of a simple or branching 
hydrocaulus rooted by a filiform anastomosing hydrorhiza, the 
whole invested by a periderm. Polypites claviform, developed 
from the summits of the hydrocaulus; tentacles capitate, scat- 
tered over the body of the polypite. 
Gonosome.—Gonophores phanerocodonic, developed from the 
body of the polypite. Medusa, at the time of its liberation from 
the trophosome, nearly spherical ; manubrium simple-mouthed, 
not reaching the margin of the umbrella; radiating canals four; 
marginal tentacles two, developed from the distal extremities of 
two opposite radiating canals ; two intermediate bulbous dilata- 
tions at the intersections of the two other radiating canals with 
the circular canal; the tentacles commence with a large bulbous 
dilatation destitute of distinct ocellus, and are for the remainder 
of their extent closely set along their external sides with pedun- 
culated sacs filled with thread-cells; from the bases of the ten- 
tacula and intermediate bulbs a cecal claviform tube filled with 
thread-cells extends in the walls of the umbrella near its external 
surface and parallel to the corresponding radiating canal. 
It is almost certain that the Medusa here described is destined to 
undergo considerable change before reaching its adult state, when its 
characters will, in all probability, be those assigned by Gegenbaur to 
his genus Zanclea. A Medusa captured by M‘Crady in the open 
sea, and regarded by him (Gymnophthalmata of Charleston Har- 
bour) as a young state of a species of Zanclea, is almost identical 
with that just described. 
Zanclea implexa, Alder (sp.), = Coryne implexa, Alder, = Coryne 
Briareus, Allman, in Ann, Nat, Hist. 1859. 
