A CONTRIBUTION TO THE NATURAL HISTORY 
AND DEVELOPMENT OF PENNARIA 
TIARELLA McCr. 
CHARLES W. HARGITT. 
I. INTRODUCTORY. 
Tue observations of which the following paper is a summary 
have been carried on during three summers at the Marine Bio- 
logical Laboratory, and in part at the laboratory of the United 
States Fish Commission, from the directors of which I am very 
glad to acknowledge many courtesies and facilities for prosecut- 
ing the work. 
The circumstances attending the work have been so varied 
during the years of its continuance that it may be hoped most 
of the errors liable to hasty observation have been avoided, and 
to a considerable measure the error liable to the personal equation 
of prepossession, where time is not allowed for its elimination. 
Pennaria tiarella McCr. was first described by Ayers (52), 
under the name of G/obzeeps tiarella, who has summarized its 
generic characters in substance as follows : Polypodon rising 
from a creeping root, branched. Short stems from the branches, 
supporting each a single polyp. Polyps encircled by three 
rows of arms, basal, median and near summit ; the arms of the 
upper rows ending in globular heads. Polyp not retractile in 
tube. The name of the genus, Globiceps, from the peculiar 
form of the arms. The specific name from the number of the 
rows of arms. He gives no account of its distribution, except 
to mention that it has been taken at Sag Harbor and in Boston 
Harbor. Of its habitat he merely mentions that it occurs on 
fucus or similar substratum. 
It was later described by Leidy (55), under the name of 
Eucoryne elegans. McCrady (57) was the first to recognize its 
true affinities with the Pennaride and designated it by the 
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