AGASSIZ. NATURAL HISTORY OF THE UNITED STATES. 493 
Thaumantias convex a 
gibbosa 
y> 
5 ) 
)5 
5 > 
lineata 
pileata 
sarnica 
hemisphaerica 
inconspicua 
punctata 
Thpmpsoni 
lucifera 
5 > 
}} 
Slabberia halterata 
Sarsia tubulosaf . 
pulcbella . 
gemmifera 
„ prolifera . 
Bougainvillea britannica 
„ nigritella 
Lizzia octopunctata 
„ blondina . . . 
Modeeria formosa . . 
Euphysa aurata . . 
Steenstrupia rubra . . 
flava . . 
)) 
Oceania convexa. 
Oceania gibbosa.* * * § 
Oceania pliosphorica. 
Obelia sphserulina. 
Eucope lucifera. 
Slabberia balterata. 
Coryne pusilla. 
Ectopleura pulcbella. 
P Hybocodon gemmifera. 
? ,, prolifera. 
Margelis ramosa. 
,, nigritella. 
Lizzia octopunctata. 
„ blondina. 
Modeeria formosa. 
Eupbysa aurata. 
Steenstrupia rubra. 
„ flava. § 
Tbe Polyxenia ( Pegasia ) Alderi of Eorbes, bas been excluded 
from tbe above table, since it appears to belong to tbe PEginidoe and, 
consequently, to tbe true DiscopJiora. 
Tbe law of priority is pushed to its extreme limits by Professor 
Agassiz. When tbe same genus includes well-marked bydroid and free 
medusoid forms, he does not hesitate to adopt for both, collectively, 
tbe name first given to either. Thus Stauridia (Wright), becomes 
a synonym of Cladonema (Dujardin), and the Eleutheria of De 
Quatrefages is made to embrace the recently established Clavatella 
of Hincks. There is much to be said in favour of this mode of pro¬ 
cedure. Why, indeed, it should so often have been disregarded in 
those cases where the medusoid happened to have been the first dis¬ 
covered form,—we can only ascribe to the mischievous influence which 
theories exert on the minds of naturalists unable to realize them. 
The genus Hydra does not occur in Professor Agassiz’ list; its 
omission being, most probably, unintentional. His Syncoryna (of 
Ehrenberg, restricted), includes the Sertulariaparasitica of Cavolini, 
and the Cordylophora\\ of Allman. The new genus Syndictyon is said 
to resemble Coryne, but its hydroid is not described. Candelabrum 
* This “constitutes, probably, a distinct genus.” 
f This and the remaining species, except Modeeria formosa, would seem to be 
undoubted medusoids. 
§ Is, “perhaps, only another state of S. rubra'' 
|| Misspelt Cordylomorpha. 
