No.415.] MORTH-AMERICAN INVERTEBRATES. o 577 
Key to the Genera. 
CODONID;. 
4. With two or four marginal tentacles, equally developed. 
— 
. Tentacles and manubrium long and slender, the Tatter extending 
al 
much beyond the velum; bell hemispheric : Coryne 
2. Tentacles rather short, sont and eR. sharable acividing 
but slightly beyond velum ; bell conic Dipurena 
3. Tentacles rather stout and closely ris AS elongate henisphericsl 
and with eight rows of nematocysts . . . . Ectopleura 
4. Tentacles only two at liberation, four in maturity . . Hydricthys 
5. Tentacles very rudimentary, bell oblong . . Pennaria 
6. Bell hemispherical, with slight conical pial piojettion, tentacles 
two, often coiled within bell when disturbed . . . Perigonimus 
ae With a single conspicuous Senay others unequally developed or 
rudimentary.. 
1. Large tentacle stout and triangular, P three rudimentary ; manu- 
brium short and thic i upuaysa 
2. A single large and long Gokak. two vas anal P one rudi- 
mentary ; bell hemispherical and slightly asymmetric 
Corymorp 
3. Bell evidently asymmetrical; a single very large tentacle with 
enlarged base, from which bud proliferously pi gas meduse, 
other tentacles very rudimentary . . . . . . Hybocodon 
TIARIDÆ. 
A. Marginal tentacles two, opposite. 
1. Bell with rather pointed apical projection . . . . . Stomotoca 
B. Marginal tentacles numerous. 
1. Bell with large, globular, apical DOE uuo luris 
2. Bell without globular apical process . . . . . . Turritopsis 
MARGELID&. ` 
; : yer D h 
1. Marginal tentacles eight, symmetrically distributed 1 P (Mice vie mn 
2. Marginal tentacles eight, PEET Ei Wut vium 
3. Tentacles in eight clusters  . Xt e Liz 
4. Tentacles in four clusters ` oiis 
5. Tentacles in four clusters, "uh with an erect dun pair 
emopsis 
