806 THE AMERICAN NATURALIST. [VoL. XXXIII. 
The condition of the medusa in this species, when liberated, 
is of further interest from a systematic standpoint. Allman, 
in his monograph on the Tubularian Hydrotds, made the organ- 
ization of the medusa a diagnostic character for the separation 
of families within the group. His Hydractinidz and Podo- 
corynide differ only in details from each other, except that in 
the former the medusoid buds remain in a rudimentary condi- 
tion in the form of sporosacs, while in the latter the medusz 
are liberated and lead a free-swimming life of considerable 
duration. In the form here described we have an exactly 
intermediate condition. Should the characters used by Allman 
stand, a new family would have to be established to include 
the species here described. But it seems that they are too 
narrow at this point, and that this species should be included 
under his family Bimeride. If so, it becomes a species of 
Stylactis. For it I propose the name S. Hooferit, after Pro- 
fessor Franklin W. Hooper, the secretary of the Brooklyn 
Institute, who has contributed so much to the success of the 
laboratory at Coldspring Harbor. 
The hydroid here described is one of the most beautiful and 
graceful that has been observed. The delicacy of the indi- 
viduals seems correlated with the protection afforded the colony 
through association with the Ilyanassa and its habitat in a 
locality free from high winds. Though the color of most of 
the colonies is whitish, many are of a pink or olive green or 
yellowish tint. Its only American ally so far observed is S. 
arge, found in the Chesapeake Bay and described by S. F. 
Clarke. It differs from the latter, however, which is found 
attached to the stems of Zostera, in which the eggs develop 
into planulz before being liberated ; and in which the terminal 
portion of the hydranths are described as breaking off to estab- 
lish new colonies. 
Diagnosis of the Species S. Hoopertt.— Hydrocaulus absent ; 
hydrorhiza a network of tubes lying in one plane, from which 
arise small, simple spines and the sessile hydranths, which are 
of two kinds, nutritive and reproductive; they are similar to 
each other and extremely elongate. The nutritive hydranths 
may attain a length of two to two and a half centimeters and 
